Method for optimizing tidal therapies employing ultrafiltrate trending

ABSTRACT

A system and method for automatically adjusting a Continuous Cycling Peritoneal Dialysis (“CCPD”) therapy to minimize the potential for excess intra-peritoneal volume. The adjustments are made at the end of the drain, just prior to the next fill. The adjustments short the next fill, if necessary, to limit the intra-peritoneal volume, add a cycle, if necessary, to use all of the available dialysis solution and will average the remaining dwell time to maximize the therapeutic benefit of the therapy in the allotted time. In another embodiment, a tidal therapy using trended patient UF data is provided.

BACKGROUND

The present disclosure relates generally to peritoneal dialysis, and inparticular to peritoneal dialysis systems useful in manipulating thenumber of cycles, drain volumes and fill volumes in a multi-cycledialysis therapy. The calculations and manipulations are useful inassuring the use of all or nearly all a prescribed dialysis solutionvolume in treating a particular patient during a particular therapy.

Automated Peritoneal Dialysis (“APD”) is a natural evolution ofContinuous Ambulatory Peritoneal Dialysis (“CAPD”), in which the patientintroduces the entire contents of a dialysate solution bag into his/herperitoneum and allows the volume to dwell for three to six hours. Afterthe dwell period, the fluid is drained using gravity. The above processis typically repeated three or four times each day as necessary. Workingadults may perform an exchange at home before leaving for work, one atwork during their lunch hour, one when the patient arrives home fromwork and one just before the patient goes to bed. Some school-agedpatients follow a similar routine except they perform their mid-dayexchange at school.

APD machines (sometimes called “cyclers”) perform sequential exchangesduring the night when the patient is sleeping, making APD a moreconvenient therapy. Also, the treatment is carried out in the privacy ofthe patient's home, so that others do not have to know that the patientis on dialysis. It is no surprise that most patients would prefer APDover CAPD.

However, there are some important differences between CAPD and APD. CAPDis typically performed with the patient sitting upright in a chair,whereas APD is performed with the patient lying down. The patient'sinternal catheter may work its way down into the bottom of the patient'speritoneal cavity (pelvic area) during the day when the patient is upand about so that it is not in an optimum position for draining when thepatient is in a prone or sleeping position. Even with the catheter inthe correct position, a supine or sitting position is generally betterfor draining than is the prone or sleeping position. Thus APD treatmentscan experience incomplete drains.

Continuous Cycling Peritoneal Dialysis (“CCPD”) is one popular APDtherapy because it performs a full drain after every dwell, minimizingthe potential for overfill due to the fluid that is ultrafiltered fromthe patient's body. CCPD can however present a challenge when a patientdoes not drain well. In a night therapy, the patient cannot be awakenedevery 1.5 hours, so that the patient can sit up and ensure a completedrain.

Accordingly, APD cyclers in some instances advance from drain to fillafter a minimum percentage of the patient's previous fill volume hasbeen drained, for example, when the drain flow rate has slowed down to apoint that time is being wasted that could be used for therapeuticbenefit. Alarms will typically be posted if the drain flow rate slows toa certain rate before the minimum drain percentage has been exceeded.The HomeChoice/Pro® APD cycler, provided by the assignee of the presentdisclosure, is considered one of the best draining cyclers on themarket, producing fewer alarms when compared to its competitors. Evenstill, low drain volume alarms occur relatively frequently.

An APD cycler with improved drain control is needed accordingly.

SUMMARY

As discussed above, automated Peritoneal Dialysis (“APD”) cyclersperform sequential exchanges during the night making APD a convenientdialysis therapy. An alternative PD therapy, continuous ambulatoryperitoneal dialysis (“CAPD”) is performed during the day, making CAPDmore life intrusive. During CAPD, however, the patient is awake and canmove around and sit up during drains, allowing drains to be performedcompletely.

At night, when the patient is performing APD, the patient is lying down.The patient's internal catheter may have shifted during the day, makingthe patient susceptible to an incomplete drain. The APD system of thepresent disclosure is programmed to advance to a fill if a drain flowrate slows to a certain point and a minimum drain volume has beenachieved. If the drain has not reached this minimum volume, which isoften based upon a certain percentage of the programmed fill, the systemwill alarm. When an alarm occurs, the patient is awakened, which is notdesirable. The system of the present disclosure greatly reduces thenumber of low drain alarms.

Another therapy concern enhancing the low drain problem is a limitplaced on how full the patient can be filled. Multiple incomplete drainsleave an ever increasing residual volume of fluid in the patient. If theresidual volume increases to a certain point, the next fill may push thepatient's intra-peritoneal volume (“IPV”) past an allowable limit. Thesubsequent fill may therefore be shorted to prevent overfilling, butthis may cause the treatment not to use all of the fluid for treatment.

To remedy the above, in one embodiment, the system begins a CCPDtreatment that attempts to drain the patient completely after eachdrain. When performed properly, the CCPD therapy is quite effective. Thepatient's initial drain (at night, just before bed) and final drain (inthe morning, after waking) should be relatively if not totally completebecause the patient can sit-up and move around to help move thepatient's catheter into areas of his/her peritoneum that are pocketingfluid.

It is the intermediate drains that may be difficult to completeespecially considering that the therapy needs to move along and cannotwait while a low drain flow rate occurs while attempting to drain thepatient completely. When the low flow rate is sensed, the systemdetermines that it is time to move to the next fill. If the previousdrain was almost complete, e.g., 85% of prescribed, the system in oneembodiment continues to provide the prescribed CCPD therapy. If allsubsequent drains are complete, the final drain can remove theadditional, e.g., 15%, fluid from the delinquent drain.

If multiple “almost complete” drains occur, the patient can begin tobuild a substantial residual volume due to the cumulative effects of theincomplete drains. If the system determines that a next fill willincrease the patient's intra-peritoneal volume (“IPV”) past an allowablevolume, e.g., 1.9 times the prescribed fill volume, the system switchesto a tidal therapy that reduces the prescribed drain to a tidal volume,increasing the likelihood of the system having a subsequent successfuldrain. The tidal therapy also reduces succeeding fills, such that thepatient's IPV does not exceed the allowable limit.

The now tidal therapy may add one or more cycle if needed to use all ofthe prescribed fresh solution. A logic flow diagram is shown below withvarious equations for determining when the one or more additional cycleis needed. Whether or not a cycle is added, the system divides theremaining unused therapy fluid and the remaining therapy time evenlyover the number of remaining cycles.

The switch to tidal therapy attempts to reduce low drain alarms thatoccur if the actual drain does not meet a threshold percentage, e.g.,85%, of the prescribed drain. The tidal therapy allows for a largerresidual volume to reside within the patient at the end of a drain,increasing the likelihood that a flow rate at the end of the drain willbe high and that the drain will not be ended early due to a low drainflow rate. The tidal therapy uses all of the remaining fresh dialysate,so that the patient is not deprived of any therapeutic benefit. Thetidal therapy is also completed on time and ensures that the patient isnot overfilled with dialysis fluid at any time.

In one embodiment, a dialysis system is provided, the dialysis systemincluding at least one dialysis fluid pump configured to pump a dialysisfluid to and from a patient over a treatment, the dialysis system alsoincluding a logic implementer configured to control the dialysis fluidpumped by the at least one dialysis fluid pump to and from a patientover the treatment, the logic implementer configured to use at least onetrended ultrafiltration (“UF”) data point for the patient to determinean amount of effluent dialysis fluid to remove from the patient duringat least one patient drain.

In another embodiment, the dialysis system includes at least onedialysis fluid pump to pump a dialysis fluid to and from a patient overa treatment, the dialysis system also including a logic implementerconfigured to control the dialysis fluid pumped by the at least onedialysis fluid pump to and from a patient over the treatment, the logicimplementer configured to (i) store a trend of ultrafiltration datapoints for the patient, and (ii) use at least one of the UF data pointsto predict the patient's intra-peritoneal volume (“IPV”) at an end of atleast one dwell.

In yet another embodiment, a dialysis system includes at least onedialysis fluid pump configured to pump a dialysis fluid to and from apatient over a treatment, the system also including a logic implementerconfigured to control the dialysis fluid pumped by the at least onedialysis fluid pump to and from a patient over the treatment, the logicimplementer configured to (i) store a trend of ultrafiltration datapoints for the patient, and (ii) use one of the UF data points in atidal treatment to predict a residual volume of effluent fluid left inthe patient's peritoneum after at least one drain.

In one embodiment, a tidal therapy is provided in which a predictedamount of patient UF for each cycle is obtained from a trend of a UFvalues for the patient, for the tidal therapy, and for a particulardialysate, having a particular osmotic agent or dextrose level. In thismanner, UF can be predicted very accurately.

Knowing predicted UF accurately allows the system to predict thepatient's intraperitoneal volume or IPV very accurately. For example,assuming that the patient's initial drain is a successful complete drain(patient awake), the patient is then filled to a known level. Thesubsequent dwell will remove an amount of UF from the patient thatshould closely approximate the predicted removal of UF. Thus the actualIPV at the end of the dwell should closely approach the actual fillamount (which is known) plus a predicted UF removed (which is based ontrended UF).

The UF trend is stored and updated in one embodiment at the cycler orautomated peritoneal dialysis (“APD”) machine. The patient can recallthe trend at any time to view same including historical trending data.The APD machine can be linked via a data network, such as an internet,so that a dialysis clinician or doctor can also view the patient's UFtrend remotely. In an alternative embodiment, the UF trend is stored andupdated on a remote server, which the patient can access via the datanetwork.

The UF trend in one embodiment plots patient single day UF data. If thepatient removes 2000 ml of UF on day X, 2000 ml is recorded for day X.And the daily UF in one embodiment is the UF removed over the nightlytreatment, that is, the UF removed after the initial drain (fromprevious days last fill or from day exchange) and prior to the lastfill, if provided. Here, the daily UF is that removed over the course ofmultiple tidal dwells. This total UF can be measured accurately becausethe patient is drained completely on the initial drain. The measured UF,which is entered into the trend is then the total amount of drainedfluid, not including the initial drain, but including the last drain,which is typically a complete drain with the patient awake, less thetotal amount of fresh dialysis fluid pumped to the patient, but notincluding the final fill. The APD machine can measure each of thesevalues accurately to provide a true UF data point.

In an alternative embodiment, the trended UF data is averaged UF datafor a particular therapy using a particular dialysate glucose level. Theaverage can for example be a rolling seven or thirty day average thataverages the last seven or thirty day's UF entries, respectively, foreach dialysate glucose solution used by the patient, to form a rollingaverage UF volume for such glucose level solution. Such averaging tendsto smooth UF anomalies for treatments that may have undergone unusualevents, such as alarms or other stoppage.

In view of the above embodiments, it is accordingly an advantage of thepresent disclosure to provide improved Continuous Cycling PeritonealDialysis (“CCPD”) and tidal automated peritoneal dialysis (“APD”)therapies.

Another advantage of the system of the present disclosure is to providean APD therapy that tends to limit low drain alarms.

A further advantage of the system of the present disclosure is toprovide an APD therapy that tends to limit patient overfilling.

Yet another advantage of the system of the present disclosure is toprovide an APD therapy that tends use all available fresh dialysis fluidover the course of treatment.

A further advantage of the system of the present disclosure is toprovide an APD therapy that adjusts to an incomplete drain to prevent apatient overfill.

Still another advantage of the system of the present disclosure is toprovide an APD therapy that reacts to an incomplete drain to ensure thatall available treatment fluid is used over the course of treatment.

Still a further advantage of the system of the present disclosure is toprovide an APD therapy that employs ultrafiltration (“UF”) trending toprovide trending data that allows for accurate prediction of UF andoverall intra-peritoneal volume (“IPV”).

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of one embodiment of a dialysis systemhaving a drain and fill sequence according to the present disclosure.

FIG. 2 is a perspective view of one embodiment of a disposable cassetteoperable with the dialysis system having a drain and fill sequenceaccording to the present disclosure.

FIG. 3 is an intra-peritoneal volume (“IPV”) versus time graph showingan example therapy in which a continuous cycling peritoneal dialysis(“CCPD”) treatment is performed according to a prescribed therapy.

FIG. 4 is an IPV versus time graph showing an example therapy in which acontinuous cycling peritoneal dialysis (“CCPD”) treatment uses a totalvolume of dialysis fluid but accumulates a large IPV due to incompletedrains.

FIG. 5 is an IPV versus time graph showing an example therapy in which acontinuous cycling peritoneal dialysis (“CCPD”) treatment accumulatesless IPV than the treatment of FIG. 4 but does not use a total volume ofdialysis fluid.

FIGS. 6A-6C are IPV versus time graphs showing two example therapyperformed according to the principles of the present disclosure.

FIGS. 7A-7E are IPV versus time graphs showing additional exampletherapies performed according to the principles of the presentdisclosure.

FIG. 8 is a chart showing percentages of when low drain alarms occurrelative to how much fluid has been drained from the patient when thealarm occurs.

FIGS. 9 and 10 is an IPV versus time graph showing other exampletherapies performed after an occasion when a previous fill uses lessthan, more than, respectively, a prescribed amount of fresh dialysate.

FIGS. 11A-11C are logic flow diagram illustrating embodiments of methodsperformed by the system of the present disclosure.

FIG. 12 is one example of a trend of UF removed from a patient over anumber of treatment days, and for different dextrose level dialysatesused, the trend used in combination with a tidal PD therapy.

FIGS. 13 to 16 are IPV versus time graphs showing various examples of atidal therapy performed using patient trended UF data.

FIG. 17 is another example of a rolling average trend of UF removed froma patient over a number of treatment days.

FIG. 18 is an IPV versus time graph showing one example of a tidaltherapy performed using patient trended UF data, and in which UF isremoved gradually from the patient over a dwell to limit the IPV.

DETAILED DESCRIPTION Dialysis System Generally

Referring now to the drawings and in particular to FIGS. 1 to 2, a renalfailure therapy system 10 is provided. System 10 is applicable generallyto any type of automated peritoneal dialysis (“APD”) system. System 10in the illustrated embodiment includes a dialysis instrument 12.Dialysis instrument 12 is configured for the type of APD therapy systemprovided. Dialysis instrument 12 includes a central processing unit(“CPU”) and memory, and may include one or more additional processor andmemory (e.g., safety, valve, heater, pump, video and audio (e.g., voiceguidance) controllers) operable with the CPU, the totality of which maybe called a logic implementer. The logic implementer operates with auser interface (“UI”) such as a graphical user-machine interface(“GUI”), e.g., via a video controller component of the logicimplementer. The GUI includes a video monitor 20 and one or more typesof input devices 22, such as a touch screen or electromechanical inputdevice (e.g., a membrane switch).

The logic implementer in cooperation with video monitor 20 providestherapy instructions and setup confirmation to the patient or caregivervisually via characters/graphics. For example, characters/graphics canbe displayed to (i) provide instructions regarding placement of a distalend of the patient line onto instrument 12 (discussed below) for primingand/or (ii) inform the patient when the patient line has been primedfully. Additionally or alternatively, a voice guidance controller of thelogic implementer in cooperation with speakers 24 provides (i) and/or(ii) listed above.

As seen in FIG. 1, dialysis instrument 12 accepts and operates with adisposable set 30. Disposable set 30 includes one or more supply bag 32a to 32 c (referred to herein collectively as supply bags 32 orindividually, generally as supply bag 32), shown here as dual-chambersupply bags separating two fluids via a peel or frangible seal 34.Disposable set 30 also includes a drain bag (not illustrated), a warmerbag 36, and patient tubes 38 a to 38 d, respectively (referred to hereincollectively as tubing or tubes 38 or individually, generally as tube38) and a disposable pumping/valve cassette 50 (FIG. 2).

Warmer bag 36 is used in a batch heating operation in which the top ofinstrument 12 batch heats fluid within bag 36. System 10 can also pumpspent fluid to a house drain, such as a bathtub, a toilet or sink,instead of to a drain bag, in which case the drain bag is not needed.

While three supply bags 32 are shown, system 10 can employ any suitablenumber of supply bags. Supply bags 32 are shown having multiple chambers42 a and 42 b, separated by frangible seal 34, which hold differentsolutions depending on the type of therapy employed. For example,chambers 42 a and 42 b can hold buffer and glucose for an overall PDdialysate having a desired glucose level. Supply bags 32 arealternatively single chamber bags, which hold a single premixedsolution, such as premixed PD dialysate having a desired glucose level.

As seen in FIGS. 1 and 2, a disposable cassette 50 connects to supplybags 32, drain bag and warmer bag 36 via tubes 38 a, 38 b and 38 c,respectively. Tube 38 d runs from cassette 50 to a patient connection44. Cassette 50 in one embodiment includes a rigid structure havingrigid outer walls 52 and a middle, base wall (not shown) from which pumpchambers (60 a and 60 b as shown in FIG. 2), valve chambers (e.g.,volcano valve chambers) and rigid fluid pathways extend. Rigid fluidports 56 extend from a side wall 52 and communicate fluidly with therigid cassette pathways and connect sealingly to tubing 38. Tubing 38can be fixed to ports 56, in which case the bags 32 are spiked to allowfluid from the bags to flow through tubing 38 into cassette 50.Alternatively, tubing 38 is fixed to bags 32, in which case ports 56 arespiked to allow fluid from the bags 32 and tubing 38 into cassette 50.

A pair of flexible membranes or sheets 58 (only one shown) is sealed toouter rigid walls 52 of the cassette. Cassette 50 is sealed withininstrument 12 such that sheeting 58 forms the outer surfaces of therigid fluid pathways of the cassette. One of the sheets is moved to pumpfluid through pump chambers (60 a and 60 b) and to open and close thecassette valves.

Instrument 12 can actuate the pump and valve chambers of cassette 50pneumatically, mechanically or both. The illustrated embodiment usespneumatic actuation. The HomeChoice® APD system uses a pneumatic systemdescribed in U.S. Pat. No. 5,350,357 (“the '357 patent”), the entirecontents of which are incorporated herein by reference. As seen in FIG.2, instrument 12 includes a flexible membrane 14, which createsdifferent sealed areas with cassette sheeting 58 at each of the pump andvalve chambers of cassette 50. Membrane 14 moves with the sheeting 58 inthose areas to either open/close a valve chamber or pump fluid through(into and out of) a pump chamber. An interface plate (not shown) islocated behind membrane 14 and includes first and second chamber halves(not shown) that mate with chamber halves 60 a and 60 b of cassette 50to form a pair of fixed volume pump chambers.

Instrument 12 in the illustrated embodiment includes a door 16, whichcloses against cassette 50. Door 16 includes a press plate 18, which canbe operated mechanically (e.g., via the closing of the door) and/orpneumatically (e.g., via an inflatable bladder located in the doorbehind the press plate). Pressing plate 18 against cassette 50 in turnpresses cassette 50 against pumping membrane 14, which cooperates withsheeting 58 of cassette 50 to pump fluid through chambers 60 a and 60 band to open and close the cassette valve chambers.

The cassette interface plate is located behind membrane 14. Cassetteinterface plate is configured to apply positive or negative pressure tothe cooperating membrane 14 and cassette sheeting 58 at the differentvalve and pump areas. For example, positive pressure is applied tomembrane 14/sheeting 58 at areas of the membrane/sheeting located withinthe internal walls of cassette 50 that define pump chambers 60 a and 60b to push fluid out of the pump chambers and within the chamber halvesof the interface plate (not shown). Negative pressure is applied tomembrane 14/sheeting 58 at those same areas to pull fluid into the pumpchambers. Likewise, positive pressure is applied to membrane 14/sheeting58 at areas of the sheeting within the internal walls of cassette 50 andthe interface plate defining the valve chambers to close outlet ports ofthe valve chambers. Negative pressure is applied to membrane 14/sheeting58 at those same areas to open the outlets of the valve chambers.

U.S. Pat. No. 6,814,547 (“the '547 patent”) assigned to the assignee ofthe present disclosure, discloses a pumping mechanism in connection withFIGS. 17A and 17B and associated written description, incorporatedherein by reference, which uses a combination of pneumatic andmechanical actuation. FIGS. 15, 16A and 16B of the '547 patent andassociated written description, incorporated herein by reference, teachthe use of mechanically actuated valves. One or both of these mechanismscan be used instead of the purely pneumatic system of the HomeChoice®machine.

The '357 patent and the '547 patent also teach different systems andmethods, incorporated herein expressly by reference, of knowing andcontrolling the amount of fresh dialysate delivered to the patient, theamount of effluent dialysate removed from the patient, and thus theamount of additional fluid or ultrafiltrate (“UF”) removed from thepatient. UF is the blood water that the patient accumulates betweentreatments due to the patient's failed kidneys. The dialysis treatmentremoves this blood water as UF in an attempt to bring the patient backto his or her dry weight. Either of the systems and method of the '357patent and the '547 patent can be used as described below forcontrolling the fill and drain volumes according to the methods ofsystem 10.

Drain and Fill Logic for Automated Peritoneal Dialysis

Referring now to FIG. 3, one example plot of the intra-peritonealpatient volume (“IPV”) versus time over an ideal CCPD for system 10 isillustrated. Here, each drain empties completely the fluid from thepatient's peritoneum, including the previous fill volume plus any UFthat has occurred during the previous dwell period. As seen in FIG. 3,therapy starts with an initial drain to empty, followed by a number ofidentical cycles consisting of a fill to a prescribed volume, a dwell ofa prescribed duration, and a drain that removes the original fill volumeplus all of the UF that has been absorbed from the patient. FIG. 3illustrates a five cycle therapy having a 2000 ml fill volume and 150ml/cycle UF volume. The initial drain recovers all of the fluid from theprevious day's last fill that has remained in the patient's peritonealcavity throughout the day.

Patients sometimes pocket fluid so that a drain that is supposed to beto empty does not remove all of the previous fill volume. System 10 inone embodiment sets a minimum drain percentage that must be obtainedwhen the fluid flow slows or stops. If the minimum drain volume is notmet, system 10 posts a low drain volume alarm. In such a case, thetherapy does not advance to fill, that is, if the drain volume is notequal to or greater than the minimum drain percentage. In FIG. 3, system10 fills the patient to the prescribed fill volume in each fill becausethe minimum drain percentage for each drain has been met. One exampleminimum drain percentage for system 10 is about 85% of the fill volume.

System 10 in one embodiment calculates the amount of UF obtained at theend of the drain phase of each cycle as follows:UF=sum of the volumes drained−sum of the volumes filled

The initial drain and last fills are not included in the UF calculation.Calculated UF will be positive as long as more spent fluid drained thanfresh dialysis fluid filled. A zero UF value means that the volumedrained after any number of cycles is equal to the volume filled duringthose cycles. A drain that does not recover all of the fluid that wasdelivered to the patient during the previous fill results in a negativeUF determination. Unless the patient is absorbing fluid, a negative UFimplies that the patient's intra-peritoneal volume is in excess of aprescribed fill volume.

It is normal for the intra-peritoneal volume to exceed the prescribedfill volume. The intra-peritoneal volume during a CCPD dwell phaseconsists of the following volumes: intra-peritoneal volume(“IPV”)=prescribed fill volume+residual volume at end of a previousdrain+UF from dwell. It is also not unusual for the residual volume inthe patient's peritoneum to equal 5 to 10% of the prescribed fill volumeat the end of a drain cycle.

The UF that has accumulated during a dwell will depend upon the osmoticgradient (a function of the dextrose level of the dialysate), the timein dwell and the transport characteristics of the patient's peritoneum.UF can range from zero to 25% of the prescribed fill volume. Thus, it isnot unusual for the intra-peritoneal volume reach about 130% of theprescribed fill volume. In practice, it is expected that the IPV willvary between 100 and 130% of the prescribed fill volume.

When the residual volume at the end of drain increases, e.g., to morethan five or ten percent of the prescribed fill volume, the patient'sintra-peritoneal volume increases accordingly during the next fill anddwell. If system 10 sets an 85% minimum drain percentage limit, theincrease in residual volume is limited to 15% per cycle plus the actualUF obtained during the cycle. Successive fill cycles after successivedrains just meeting the 85% minimum drain percentage requirement willcause the patient's intra-peritoneal volume to increase at eachsuccessive cycle. System 10 also tracks cumulative UF and places a limiton the maximum negative UF value allowed. If this value is exceeded atany time during a therapy, system 10 will not advance from drain phaseto the next fill phase even if the minimum drain percentage has been metwhen the drain ends. System 10 in one embodiment allows the patient orcaregiver, in certain instances, to override the negative UF alarm andallow the therapy to advance to the next fill.

FIG. 4 illustrates a therapy in which successive drains just meet theminimum 85% drain volume and system 10 advances the therapy in each caseto the next full fill. System 10 allows the intra-peritoneal volume toincrease past the 130% of prescribed fill volume limit (2600 ml, afterthird fill), through the 160% of prescribed fill volume limit (3200 ml,after fourth fill) and into the 190% of prescribed fill volume limit(3800 ml, after fifth fill). The actual UF per cycle in the therapy ofFIG. 4 is 150 ml per cycle which equals 7.5% of the 2000 ml fill volume.

System 10 in FIG. 4 posts a negative UF alarm when drain 4 ends with theminimum drain percentage just met because the cumulative negative UF hasreached its limit, e.g., 1200 ml (four drains×15% of 2000 ml). Thepatient or caregiver in the illustrated example elects to bypass thenegative UF alarm, so that system 10 advances to the fifth full fill, inwhich case the patient's intra-peritoneal volume exceeds a 190% of thefill volume limit (1.9×2000=3800 ml).

The therapy illustrated by FIG. 4 fills the patient with 2000 ml offluid during each of the night fills using all 10,000 ml of solutionavailable for use during therapy. However, during this therapy, thepatient's IPV reaches 3950 ml, which is 197.5% of the prescribed fillvolume. Furthermore, the patient encounters and has to address an alarm(negative UF) that interrupts his/her sleep.

FIG. 5 is illustrative of a therapy per the first step in an embodimentin which the patient volume stays below 190% of the prescribed fillvolume. The patient does not encounter any alarms during the night. Asseen, the therapy of FIG. 5 encounters the same drain issues as thetherapy illustrated in FIG. 2. Drains 1 through 4 each end with only 85%of the preceding fill volume recovered. Cumulative negative UF increasesin 15% steps to 45% at the end of drain 3.

System 10 in the example of FIG. 4 places a 40% limit on negative UF (asopposed to 60% (=1200/2000 in FIG. 4), so that system 10 causes Fill 4to be shorted by 5%, limiting the negative UF at 40%. System 10 shortsFill 5 by 15% because Drain 4 was also 15% short. The maximum value forthe IPV is 3550 ml (177.5% of prescribed fill volume) during thistherapy. The 40% negative UF limit could have been set to a lower value,such as 30%, limiting the maximum IPV to 3250 ml.

The therapy illustrated in FIG. 5 prevented the IPV from exceeding 190%of the prescribed fill volume but did allow the IPV to exceed 160% ofthe prescribed fill volume. The therapy of FIG. 5 used only 9,600 ml ofthe 10,000 ml of dialysis fluid that was available. Assuming the fluidcould have been used to its maximum potential, the therapy illustratedin FIG. 3 was 96% effective in delivering the maximum possibletherapeutic benefit. The therapies illustrated in FIGS. 3 and 4, on theother hand, were 100% effective.

The therapies illustrated in FIGS. 4 and 5 are considered to be CCPDtherapies because all drains are prescribed to go to empty. The onlydrains that actually made it to empty, however, were the initial drainand the last drain in which the patient was awake and could move around,or sit up, to drain fully. The CCPD therapies are accordinglypseudo-tidal in nature. If they had been programmed as tidal therapieswith a tidal percent of 85%, all of the drains in FIGS. 4 and 5 wouldhave ended when 85% of the programmed fill volume plus expected UF hadbeen drained. The following fills would have brought the patient volumeback to 100% of the programmed fill volume.

FIGS. 6A-6C and FIGS. 7A-7E demonstrate the operation of steps 2 and 3of a method of one embodiment, with respectively, 75% and 65% tidalvolumes, rather than the 85% discussed above with respect to FIG. 5. InFIGS. 6A-6C, the operation of a 75% tidal system is depicted, each withan additional cycle as compared to FIG. 5. In FIG. 6A, the systemoperates as intended, and in this case, an “ideal” patient responds asintended. In FIG. 6A, 2000 ml is used for the first, 100% fill, and alldrains except the first and the last are about 1698 ml. This represents75% of a 2105 ml fill volume and a calculated 120 ml UF. Note that 6cycles with 120 ml of UF would remove a total of about 720 mlultrafiltrate over the duration of the nocturnal therapy. The patientvolume does not appear to reach even 2200 ml, i.e., does not even reach10% over the initial patient volume (IPV). As seen in FIG. 6A, eachcycle lasts about 1.5 hours and there are a total of six cycles, for a9-hour therapy, from about 10:30 pm to about 7:30 the next morning.

In FIG. 6B, the same 2105 ml fill volume is used, but in this case, thepatient does not drain as expected. The same drain volume, about 1698ml, is expected, but does not occur in every drain cycle. In the firstdrain cycle, only about 1450 ml is drained. In addition, drains 3 and 4are also short, as can be seen by observing the increasing patientvolume fill. Even in this situation, however, the peak patient fillvolume appears to reach about 2800 ml, i.e., about 140% of IPV, which isnot ideal but is considerably less than the 161% required for a“moderate excess” intraperitoneal volume and is far less than theprevious situation seen in FIG. 4 or FIG. 5.

The total prescribed therapy volume is also used in the therapy depictedin FIG. 6C. In FIG. 6C, cycles 1, 3, 4 and 5 have short drains, as seenby the increasing patient fill volume over the six cycles, rising toalmost 3000 ml. The tidal therapy shown in FIG. 6C shorts the last fillby about 100 ml in order to limit the IPV to 140% of the prescribed fillvolume. This reduces the effectiveness of the 10,000 ml night therapy byabout 1% based upon the actual fluid volume used, (10000−100)/10000=99%.Note that no alarms were necessary in any of the therapies depicted inFIGS. 6A-6C.

If a fluid volume exceeding a predetermined limit remains unused nearlyevery day, a switch can be made from a 75% tidal therapy to a 65% tidaltherapy allowing the based residual volume to increase by another 10%.FIGS. 7A-7E illustrate how such a therapy would limit the IPV whileusing all of the available fluid and maintaining the predicted dwelltimes. The patient would seldom get a low drain volume alarm or anegative UF alarm when the base therapy is assumed to be tidal insteadof CCPD. In FIG. 7A, the therapy is now 65% tidal therapy, with 2additional cycles over those of FIG. 5 required in order to use thetotal prescribed therapy volume. FIG. 7A depicts a relatively idealsituation, in which a patient has all drains, except the first and thelast, at about 1436 ml, representing 65% of 2040 ml of fill volume and110 ml UF (110 ml UF over 7 cycles would remove about 770 ml UF). Eachcycle is now a little shorter, about 1 hour and 15 minutes, for a totaltherapy time of about 8 hours and 45 minutes. In this idealizedsituation, the patient fill volume does not exceed 2200 ml, that is,does not go over about 110% of the prescribed fill volume.

The patient response in FIG. 7B is somewhat less ideal, with the firstdrain about 200 ml short (about 10% less than expected). Each drain isexpected to be about 1436 ml, with 65% of 2040 ml fill volume (1326 ml)and 110 ml UF. While the first drain is short, the remaining drains areon target until the last drain, which is about 2350 ml. This therapy isstill very well-behaved, with no alarms and patient IPV not exceedingthe negligible excess level (less than 130% IPV). In FIG. 7C, however,several drains are short, e.g., the first and second drains are about200 ml short. The tidal therapy is offset each time by the 200 ml drainshortage, i.e., the tidal therapy volume increases by about 200 ml.Nevertheless, since the patient volume does not exceed the negligibleexcess level, the subsequent fills on cycles 2 and 3 are not shorted.Thus, the total therapy volume is used and the patient is still notupset by unnecessary alarms during the nocturnal therapy. Of course, ifthe volume were to exceed one of the thresholds, the controls could beprogrammed to short one or more of the cycle fill volumes.

FIG. 7D depicts another patient therapy with some of the sameshortcomings as FIG. 7C. As in FIG. 7C, there are two additional cyclesand two short drains, drains 1 and 4, as seen by the increase in IPV atcycles 2 and 5. The negligible excess level is not exceeded, and asbefore, there are no alarms since the IPV level does not exceed thenegligible excess level of less than 130% of patient volume. The totaltherapy volume is also used in this situation. FIG. 7E depicts anothertherapy performance. In this depiction, the first, second and fourthdrains are each short by about 200 ml. Thus, the total patient volumerises by about 600 ml, which is still within the negligible excess IPVlimit.

The therapies of FIGS. 6A-6C and FIGS. 7A-7E limit the maximum patientfill volume while using all the dialysis solution that is prescribed andavailable. At the same time, the therapy may be programmed to withholdtherapy volume if the patient drain is much less than expected and thepatient fill volume would cross an unacceptable threshold. Extra cyclesmay be added, each cycle an appropriate amount shorter, so that eachfill is as effective as possible, the available solution is used, theavailable time is used, and alarms that disturb and disrupt a patientare kept to a minimum.

If drains continue to be shorted beyond the three shown in FIG. 7E,however, such that maximum IPV grows (or is predicted to grow) to 2650ml or greater (thirty percent or greater than initial fill volume),system 10 will stop offsetting the base patient volume and will shortthe next fill. The offset of the base patient volume is limited to 30%of the initial fill volume less the expected UF per cycle. System 10 inone embodiment posts a low drain volume alarm if ending the drain wouldresult in an IPV on the next fill that would exceed 130% of theprogrammed fill volume not including UF. In one embodiment, system 10limits the maximum IPV to 130% of the programmed fill volume (initialfill volume for tidal therapies). The offset limit can be adjusted to avalue other than 30% if necessary, for example from 20% to 40%. Theoffset limit with tidal is similar to the negative UF limit that wasimposed on the CCPD Therapy.

The method disclosed herein may progress gradually from an 85% CCPD(pseudo tidal) therapy to a 75% tidal therapy to a 65% tidal therapy andeven to a 55% tidal therapy as it seeks to use all of the availabledialysis solution, minimize the increased intra peritoneal volume andminimize the number of low drain alarms. Patient volume offsets will beallowed as long as they do not exceed a predetermined programmable limitthat will be defaulted to 30%. Cycles will be added each time the tidalpercentage decreases so that all of the dialysis solution volume isused. The base patient fill volume may also be adjusted up or down 5-10%during this process so that no fluid volume is wasted.

As discussed in more detail below, in one embodiment, system 10 trendsUF based upon the dialysis solution used. For example, for a particularpatient, the expected UF per therapy might be 500 ml with 1.5% dextrose,750 ml with 2.0% dextrose, 1000 ml with 2.5% dextrose and 1500 ml with4.25% dextrose. System 10 in one embodiment is programmed to notify thepatient if the programmed total UF at the beginning of treatment differsby more than 20% from the trended UF for the particular dextroseconcentration being used.

It is believed that system 10 will encounter fewer low drain volumealarms and virtually no negative UF alarms when compared to current CCPDtherapies. The system will consistently use the total dialysate volumeavailable and will not allow the patient's IPV to exceed 160% of theprogrammed fill volume.

FIG. 8 shows that the occurrence of non-initial drain alarms that areposted during a therapy would be expected to decrease to less than half(0.450/0.94) its current number if the minimum drain percentage weredecreased from 85% to 65%. The alarm decrease would be to about ⅝(0.6/0.94) if the minimum drain percentage were decreased to 75% from65%.

System 10 in one embodiment also averages both the per cycle fill volumeand per cycle dwell time after manual drains or bypasses in fill thatalter the volume of fluid remaining, as will be explained below forFIGS. 11A-11C. System 10 recalculates the therapy after such manualdrain or bypass in fill that alters the volume of fluid remaining,calculating a revised average dwell time for each the remaining cycles.System 10 also calculates a revised (potentially) remaining number ofcycles, which is calculated by dividing the total remaining therapyfluid volume less a “last fill” or “wet day” fill volume by theprescribed fill volume:cycles remaining=(total remaining therapy volume−last fill volume (ifany))/programmed fill volume

System 10 in one implementation rounds up a fractional portion of acycle if it is greater than 0.4 and divides both the total remainingtherapy volume and therapy time equally over the rounded-up number ofcycles remaining. Otherwise, the calculated number of cycles istruncated, and system 10 divides both the total remaining therapy volumeand therapy time equally over the truncated number of cycles remaining.

FIGS. 9-10 illustrate how cycles can be added or at least not dropped inorder to use all of the available fluid. The same concept carries overinto drains when cycles are added. The principle is to use as much fluidas possible so as to give the maximum benefit to the patient whilewasting as little fluid as possible.

FIG. 9 illustrates a treatment in which the first fill uses less fluidthan normal because of a bypass of the fill. For example, if a userfeels full and uses a manual drain or does not use a full fill. As aresult, 500, 750 or 1000 ml of fluid (out of 2000 ml) was used in thefirst fill. System 10 spreads the remaining volume evenly over theremaining cycles, which are increased in FIG. 8 from three to four. Ifthe full 2000 ml is used in the first fill then the top or highest fillline shows that the therapy proceeds with three additional 2000 ml fillsfor total of 8000 ml. If only 500 ml is used in the first fill then thesecond or next highest fill line shows that the four fills at about 1875ml are performed to use the total 8000 ml. If only 750 ml is used in thefirst fill then the third line shows that the four fills of about 1810ml are performed to use the total 8000 ml. If only 1000 ml is used inthe first fill then the lowest of the four fill lines shows that thefour fills at about 1746 ml are performed to use the total 8000 ml. Theresult again is a more effective therapy.

FIG. 10 illustrates a scenario in which the first fill uses more fluidthan normal because of a manual drain in the first fill. Here, system 10averages the remaining therapy volume over the remaining four cyclesinstead of dropping a cycle and retaining the original fill volume. Theresult again is a more effective therapy.

Referring now to FIG. 11A, flow diagram 100 illustrates one embodimentof a system 10 which may be used in either CCPD or tidal mode. Themethod begins at oval 102. At block 104, the user sets a programmablenegative UF limit that is used to determine when to use shorter fillvolumes after one or more incomplete drains when running a CCPD therapyor a Tidal therapy. As seen in blocks 106, 108, the system 10 tracks UFand calls for a short fill if needed, in both CCPD mode and in Tidalmode.

At block 110, system 10 performs an initial drain, followed by block 112with a fill. Per block 114, for drains after the initial drain, ashorter fill volume will be used, i.e., the fill is shorted, if theprevious drain falls short of the target volume and the UF limit isexceeded. After the fill, a dwell at block 116 is performed, the dwellcalculated as discussed below. After the dwell, a drain is performed atblock 118. Based on the drain, the number of remaining cycles and thedwell time is calculated at block 120. The dwell time is calculated atblock 120 to use all the allocated therapy time. In both the CCPD andtidal modes, system 10 tracks UF, offsets the residual patient volumeand maintains the tidal fill volume if a tidal drain is incomplete aslong as the sum of the increases in residual patient volume and expectedUF do not exceed the negative UF Limit.

For CCPD therapies, system 10 calculates the remaining number of CCPDcycles using the equation: Cycles Remaining=(total remaining therapyvolume−last fill volume (if any))/(programmed fill volume)

For Tidal therapies after an incomplete tidal drain, or after a completefull drain, system 10 calculates the remaining number of tidal cyclesusing the equation: Cycles Remaining=1+(Remaining Therapy Volume−FillVolume−Last Fill Volume)/(Tidal PerCent*Fill Volume).

For Tidal therapies after a complete tidal drain, system 10 calculatesthe remaining number of tidal cycles using the equation: CyclesRemaining=(Remaining Therapy Volume−Last Fill Volume)/(TidalPerCent*Fill Volume).

At diamond 122, if the fractional number of cycles exceeds 0.85, thenumber of cycles is rounded up to the nearest integer, per block 124.For example, if the fractional number of cycles remaining is 4.9, thenumber of cycles remaining is rounded up to 5; if the number of cyclesremaining is 0.9, the number of cycles remaining is rounded up to 1. Atdiamond 126, system 10 compares the number of remaining cycles to zero.If the number of cycles remaining is greater than zero, the next fill isperformed, per block 112 and the process is repeated. If the number ofcycles is zero, the therapy is complete, per block 130.

Returning to diamond 122, if the fractional number of cycles is lessthan 0.85, the path moves to block 128, where the number of cycles isrounded down or truncated. At the next step, at diamond 126, system 10compares the number of remaining cycles to zero. If the number of cyclesremaining is greater than zero, the next fill is performed, per block112 and the process is repeated. If the number of cycles is zero, thetherapy is complete, per block 130.

Referring now to FIG. 11B, flow diagram 140 illustrates one embodimentof a system 10 which may be used in either CCPD or tidal mode. Themethod begins at oval 142. At block 144, the user sets a programmablenegative UF limit that is used to determine when to use shorter fillvolumes after one or more incomplete drains when running a CCPD therapyor a Tidal therapy. As seen in blocks 146, 148, the system 10 tracks UFand calls for a short fill if needed, in both CCPD mode and in Tidalmode.

At block 150, system 10 performs an initial drain, followed by a fill atblock 152. If the previous drain falls short of the target volume andthe UF limit is exceeded, then per block 154, for drains after theinitial drain, a shorter fill volume will be used, i.e., the fill isshorted. After the fill, a dwell at block 156 is performed, the dwellcalculated as discussed below. After the dwell, a drain is performed atblock 158. Based on the drain, the number of remaining cycles and thedwell time is calculated at block 160 in order to use all of theallocated therapy time. In both the CCPD and tidal modes, system 10tracks UF, offsets the residual patient volume and maintains the tidalfill volume if a tidal drain is incomplete, as long as the sum of theincreases in residual patient volume and expected UF do not exceed thenegative UF Limit.

For CCPD therapies, system 10 calculates the remaining number of CCPDcycles using the equation: Cycles Remaining=(total remaining therapyvolume−last fill volume (if any))/(programmed fill volume).

For Tidal therapies after a tidal drain that ends prematurely due to anempty patient, or after a tidal full drain, system 10 calculates theremaining number of tidal cycles using the equation: CyclesRemaining=1+(Remaining Therapy Volume−Fill Volume−Last FillVolume)/(Tidal PerCent*Fill Volume).

For Tidal therapies after a normal tidal drain, system 10 calculates theremaining number of tidal cycles using the equation: CyclesRemaining=(Remaining Therapy Volume−Last Fill Volume)/(TidalPerCent*Fill Volume).

At diamond 162, if the fractional number of cycles exceeds 0.85, thenumber of cycles is rounded up to the nearest integer, per block 164.For example, if the fractional number of cycles remaining is 4.9, thenumber of cycles remaining is rounded up to 5. At diamond 166, system 10compares the number of remaining cycles to zero. If the number of cyclesremaining is greater than zero, the next fill is performed, per block152 and the process is repeated. If the number of cycles is zero, thetherapy is complete, per block 170.

Returning to diamond 162, if the fractional number of cycles is lessthan 0.85, the process path moves to diamond 168. At this point, thefractional number of cycles is compared to 0.40 (40% of a cycle). If thefractional number remaining is less than 0.40, the number of cycles isrounded down, or truncated at block 172 and the process moves to diamond166, where the remaining number of cycles is compared to zero. If thenumber of cycles remaining is greater than zero, the next fill isperformed, per block 152 and the process is repeated. If the number ofcycles is zero, the therapy is complete, per block 170.

Returning to diamond 168, if the fractional number of cycles is greaterthan 0.40, a new higher fill volume is calculated with a truncatednumber of cycles at block 174. At diamond 176, the ratio of IncreasedFill to Prescribed Fill is calculated. If the ratio is not greater than1.05, i.e., the volume increase is less than 5%, the increased fillvolume is taken as the new set point at block 178. The number of cyclesis truncated at block 172, and the number of remaining cycles is thencompared to zero at diamond 166. If no cycles remain, the therapy iscompleted at block 170. If 1 or more cycles remains, the processadvances to block 152 and is repeated.

Returning to diamond 176, if the increase is greater than 5%, adecreased fill volume is calculated, based on a rounded-up number ofcycles at block 180. The number of cycles is rounded up at block 182 andthe set fill volume is reset to a decreased fill volume. The processthen returns to diamond 166 for another cycle if appropriate.

Example for Patient A: Tables 1, 2, 3 and 4 contain system 10 drainvolume/fill volume (DV/FV) ratios, UF/fill (UF/FV) volume and ratios ofunused fluid volume/fill (Unused Fluid/FV) volume ratios for CCPDtherapies for Patient A with the negative UF limits set to 40%, 30%, 25%and 20%, respectively. The average drain volume/fill volume ratio inDrain 5 of 5 decreases as the fraction of unused fluid volume increaseswhen the negative UF limit decreases from 40% to 20%. The maximumdrain/fill volume (DV/FV) ratio decreases from 1.69 to 1.45.

TABLE 1 5 × 2 Liter CCPD Therapy with Negative UF Limit Set to 40%Patient A DV/FV UF/FV Unused Fluid/FV Day 1 2 3 4 5 6 7 1 2 3 4 5 6 7 12 3 4 5 6 7  1 0.85 0.89 0.93 1.02 1.71 −0.15 −0.26 −0.33 −0.31 0.40 0 00 0 0  2 0.85 0.87 0.97 0.96 1.75 −0.15 −0.28 −0.31 −0.35 0.40 0 0 0 0 0 3 0.87 0.89 0.94 0.95 1.75 −0.13 −0.24 −0.3 −0.35 0.40 0 0 0 0 0  40.87 0.9 0.99 1.04 1.6 −0.13 −0.23 −0.24 −0.2 0.40 0 0 0 0 0  5 0.86 0.90.94 1.04 1.66 −0.14 −0.24 −0.3 −0.26 0.40 0 0 0 0 0  6 0.85 0.9 0.930.97 1.75 −0.15 −0.25 −0.32 −0.35 0.40 0 0 0 0 0  7 0.85 0.91 0.99 0.971.68 −0.15 −0.24 −0.25 −0.28 0.40 0 0 0 0 0  8 0.85 0.89 0.98 1.04 1.64−0.15 −0.26 −0.28 −0.24 0.40 0 0 0 0 0  9 0.86 0.87 0.98 1.05 1.64 −0.14−0.27 −0.29 −0.24 0.40 0 0 0 0 0 10 0.85 0.87 0.94 0.95 1.79 −0.15 −0.28−0.34 −0.39 0.40 0 0 0 0 0 11 0.87 0.87 0.95 0.98 1.73 −0.13 −0.26 −0.31−0.33 0.40 0 0 0 0 0 12 0.85 0.89 0.97 1 1.69 −0.15 −0.26 −0.29 −0.290.40 0 0 0 0 0 13 0.85 0.89 0.98 1.04 1.64 −0.15 −0.26 −0.28 −0.24 0.400 0 0 0 0 14 0.87 0.89 0.99 1.02 1.63 −0.13 −0.24 −0.25 −0.23 0.40 0 0 00 0 15 0.87 0.87 0.95 0.99 1.72 −0.13 −0.26 −0.31 −0.32 0.40 0 0 0 0 016 0.87 0.88 0.94 1.05 1.66 −0.13 −0.25 −0.31 −0.26 0.40 0 0 0 0 0 170.85 0.9 0.95 1.04 1.66 −0.15 −0.25 −0.3 −0.26 0.40 0 0 0 0 0 18 0.850.88 0.94 1 1.73 −0.15 −0.27 −0.33 −0.33 0.40 0 0 0 0 0 19 0.87 0.910.92 1.02 1.68 −0.13 −0.22 −0.3 −0.28 0.40 0 0 0 0 0 20 0.86 0.9 0.930.99 1.72 −0.14 −0.24 −0.31 −0.32 0.40 0 0 0 0 0 AVE 0.86 0.89 0.96 1.011.69 −0.14 −0.25 −0.30 −0.29 0.40 0.00 0.00 0.00 0.00 0.00

TABLE 2 5 × 2 Liter CCPD Therapy with Negative UF Limit Set to 30%Patient A DV/FV UF/FV Unused Fluid/FV Day 1 2 3 4 5 6 7 1 2 3 4 5 6 7 12 3 4 5 6 7  1 0.86 0.88 0.96 1 1.7 −0.14 −0.26 −0.3 −0.3 0.40 0 0 0 0 0 2 0.85 0.91 0.96 0.95 1.7 −0.15 −0.24 −0.28 −0.33 0.37 0 0 0 −0.03−0.03  3 0.87 0.89 0.93 0.98 1.69 −0.13 −0.24 −0.31 −0.33 0.36 0 0 −0.01−0.04 −0.04  4 0.86 0.91 0.93 1.02 1.68 −0.14 −0.23 −0.3 −0.28 0.40 0 00 0 0  5 0.85 0.87 0.92 0.98 1.64 −0.15 −0.28 −0.36 −0.38 0.26 0 0 −0.06−0.14 −0.14  6 0.86 0.89 0.92 1.01 1.67 −0.14 −0.25 −0.33 −0.32 0.35 0 0−0.03 −0.05 −0.05  7 0.85 0.9 0.98 1 1.67 −0.15 −0.25 −0.27 −0.27 0.40 00 0 0 0  8 0.86 0.9 0.95 1.05 1.64 −0.14 −0.24 −0.29 −0.24 0.40 0 0 0 00  9 0.87 0.88 0.92 1.04 1.66 −0.13 −0.25 −0.33 −0.29 0.37 0 0 −0.03−0.03 −0.03 10 0.85 0.91 0.95 1.04 1.65 −0.15 −0.24 −0.29 −0.25 0.40 0 00 0 0 11 0.85 0.9 0.99 1.02 1.64 −0.15 −0.25 −0.26 −0.24 0.40 0 0 0 0 012 0.85 0.87 0.91 0.97 1.63 −0.15 −0.28 −0.37 −0.4 0.23 0 0 −0.07 −0.17−0.17 13 0.87 0.89 0.93 0.99 1.69 −0.13 −0.24 −0.31 −0.32 0.37 0 0 −0.01−0.03 −0.03 14 0.87 0.89 0.95 0.95 1.7 −0.13 −0.24 −0.29 −0.34 0.36 0 00 −0.04 −0.04 15 0.86 0.9 0.96 0.98 1.7 −0.14 −0.24 −0.28 −0.3 0.40 0 00 0 0 16 0.85 0.87 0.93 0.96 1.65 −0.15 −0.28 −0.35 −0.39 0.26 0 0 −0.05−0.14 −0.14 17 0.85 0.91 0.97 1.03 1.64 −0.15 −0.24 −0.27 −0.24 0.40 0 00 0 0 18 0.86 0.91 0.91 1.04 1.66 −0.14 −0.23 −0.32 −0.28 0.38 0 0 −0.02−0.02 −0.02 19 0.87 0.91 0.95 1.01 1.66 −0.13 −0.22 −0.27 −0.26 0.40 0 00 0 0 20 0.87 0.89 0.99 0.99 1.66 −0.13 −0.24 −0.25 −0.26 0.40 0 0 0 0 0AVE 0.86 0.89 0.95 1.00 1.67 −0.14 −0.25 −0.30 −0.30 0.37 0.00 0.00−0.01 −0.03 −0.03

TABLE 3 5 × 2 Liter CCPD Therapy with Negative UF Limit Set to 25%Patient A DV/FV UF/FV Unused Fluid/FV Day 1 2 3 4 5 6 7 1 2 3 4 5 6 7 12 3 4 5 6 7  1 0.87 0.9 0.95 0.95 1.62 −0.13 −0.23 −0.28 −0.33 0.29 0 0−0.03 −0.11 −0.11  2 0.87 0.89 0.92 1.04 1.58 −0.13 −0.24 −0.32 −0.280.30 0 0 −0.07 −0.1 −0.1  3 0.86 0.91 0.91 1 1.58 −0.14 −0.23 −0.32−0.32 0.26 0 0 −0.07 −0.14 −0.14  4 0.86 0.89 0.93 0.98 1.58 −0.14 −0.25−0.32 −0.34 0.24 0 0 −0.07 −0.16 −0.16  5 0.86 0.88 0.95 1.05 1.58 −0.14−0.26 −0.31 −0.26 0.32 0 −0.01 −0.07 −0.08 −0.08  6 0.86 0.91 0.91 1.021.58 −0.14 −0.23 −0.32 −0.3 0.28 0 0 −0.07 −0.12 −0.12  7 0.87 0.89 0.930.99 1.59 −0.13 −0.24 −0.31 −0.32 0.27 0 0 −0.06 −0.13 −0.13  8 0.850.89 0.99 0.95 1.62 −0.15 −0.26 −0.27 −0.32 0.30 0 −0.01 −0.03 −0.1 −0.1 9 0.87 0.89 0.99 1.02 1.63 −0.13 −0.24 −0.25 −0.23 0.40 0 0 0 0 0 100.86 0.89 0.98 0.97 1.63 −0.14 −0.25 −0.27 −0.3 0.33 0 0 −0.02 −0.07−0.07 11 0.86 0.91 0.96 0.98 1.63 −0.14 −0.23 −0.27 −0.29 0.34 0 0 −0.02−0.06 −0.06 12 0.85 0.89 0.95 1.01 1.58 −0.15 −0.26 −0.31 −0.3 0.28 0−0.01 −0.07 −0.12 −0.12 13 0.87 0.87 0.99 0.99 1.62 −0.13 −0.26 −0.27−0.28 0.34 0 −0.01 −0.03 −0.06 −0.06 14 0.85 0.87 0.99 1.04 1.58 −0.15−0.28 −0.29 −0.25 0.33 0 −0.03 −0.07 −0.07 −0.07 15 0.87 0.89 0.94 1.031.6 −0.13 −0.24 −0.3 −0.27 0.33 0 0 −0.05 −0.07 −0.07 16 0.85 0.87 0.961.02 1.55 −0.15 −0.28 −0.32 −0.3 0.25 0 −0.03 −0.1 −0.15 −0.15 17 0.850.89 0.98 0.99 1.61 −0.15 −0.26 −0.28 −0.29 0.32 0 −0.01 −0.04 −0.08−0.08 18 0.86 0.91 0.97 0.96 1.64 −0.14 −0.23 −0.26 −0.3 0.34 0 0 −0.01−0.06 −0.06 19 0.87 0.89 0.92 1.04 1.58 −0.13 −0.24 −0.32 −0.28 0.30 0 0−0.07 −0.1 −0.1 20 0.86 0.88 0.97 0.95 1.6 −0.14 −0.26 −0.29 −0.34 0.260 −0.01 −0.05 −0.14 −0.14 AVE 0.86 0.89 0.95 1.00 1.60 −0.14 −0.25 −0.29−0.30 0.30 0.00 −0.01 −0.05 −0.10 −0.1

TABLE 4 5 × 2 Liter CCPD Therapy with Negative UF Limit Set to 20%Patient A DV/FV UF/FV Unused Fluid/FV Day 1 2 3 4 5 6 7 1 2 3 4 5 6 7 12 3 4 5 6 7  1 0.86 0.9 0.96 0.95 1.48 −0.14 −0.24 −0.28 −0.33 0.15 0−0.04 −0.12 −0.25 −0.25  2 0.87 0.87 0.93 0.98 1.41 −0.13 −0.26 −0.33−0.35 0.06 0 −0.06 −0.19 −0.34 −0.34  3 0.85 0.89 0.97 1 1.45 −0.15−0.26 −0.29 −0.29 0.16 0 −0.06 −0.15 −0.24 −0.24  4 0.87 0.89 0.94 1.021.46 −0.13 −0.24 −0.3 −0.28 0.18 0 −0.04 −0.14 −0.22 −0.22  5 0.85 0.910.99 1 1.51 −0.15 −0.24 −0.25 −0.25 0.26 0 −0.04 −0.09 −0.14 −0.14  60.87 0.89 0.96 0.95 1.48 −0.13 −0.24 −0.28 −0.33 0.15 0 −0.04 −0.12−0.25 −0.25  7 0.85 0.89 0.96 0.96 1.44 −0.15 −0.26 −0.3 −0.34 0.10 0−0.06 −0.16 −0.3 −0.3  8 0.86 0.88 0.96 1.05 1.44 −0.14 −0.26 −0.3 −0.250.19 0 −0.06 −0.16 −0.21 −0.21  9 0.85 0.88 0.96 1.04 1.42 −0.15 −0.27−0.31 −0.27 0.15 0 −0.07 −0.18 −0.25 −0.25 10 0.86 0.91 0.92 1 1.46−0.14 −0.23 −0.31 −0.31 0.15 0 −0.03 −0.14 −0.25 −0.25 11 0.86 0.87 0.950.97 1.41 −0.14 −0.27 −0.32 −0.35 0.06 0 −0.07 −0.19 −0.34 −0.34 12 0.870.9 0.91 1.05 1.45 −0.13 −0.23 −0.32 −0.27 0.18 0 −0.03 −0.15 −0.22−0.22 13 0.85 0.88 0.96 0.96 1.42 −0.15 −0.27 −0.31 −0.35 0.07 0 −0.07−0.18 −0.33 −0.33 14 0.87 0.89 0.93 1.03 1.45 −0.13 −0.24 −0.31 −0.280.17 0 −0.04 −0.15 −0.23 −0.23 15 0.87 0.88 0.98 0.96 1.48 −0.13 −0.25−0.27 −0.31 0.17 0 −0.05 −0.12 −0.23 −0.23 16 0.85 0.87 0.94 0.98 1.38−0.15 −0.28 −0.34 −0.36 0.02 0 −0.08 −0.22 −0.38 −0.38 17 0.87 0.91 0.910.99 1.47 −0.13 −0.22 −0.31 −0.32 0.15 0 −0.02 −0.13 −0.25 −0.25 18 0.870.91 0.94 1.04 1.5 −0.13 −0.22 −0.28 −0.24 0.26 0 −0.02 −0.1 −0.14 −0.1419 0.85 0.9 0.92 1.02 1.42 −0.15 −0.25 −0.33 −0.31 0.11 0 −0.05 −0.18−0.29 −0.29 20 0.86 0.91 0.96 1.03 1.5 −0.14 −0.23 −0.27 −0.24 0.26 0−0.03 −0.1 −0.14 −0.14 AVE 0.86 0.89 0.95 1.00 1.45 −0.14 −0.25 −0.30−0.30 0.15 0.00 −0.05 −0.15 −0.25 −0.25

Example for Patient B: Tables 5, 6, 7 and 8 contain system 10 drainvolume/fill volume ratios, UF/fill volume ratios and unused fluidvolume/fill volume ratios for CCPD therapies for Patient B with thenegative UF limits set to 40%, 30%, 25% and 20%, respectively. Theaverage drain volume/fill volume (DV/FV) ratio in Drain 5 of 5 decreasesas the fraction of unused fluid volume increases when the negative UFLimit decreases from 40% to 20%. The maximum DV/FV ratio decreases from1.67 to 1.43, as seen in FIG. 5-8.

TABLE 5 5 × 2 Liter CCPD Therapy with Negative UF Limit Set to 40%Patient B DV/FV UF/FV Unused Fluid/FV Day 1 2 3 4 5 6 7 1 2 3 4 5 6 7 12 3 4 5 6 7  1 0.87 0.89 0.96 1.14 1.54 −0.13 −0.24 −0.28 −0.14 0.40 0 00 0 0  2 0.86 0.93 1.05 1.03 1.53 −0.14 −0.21 −0.16 −0.13 0.40 0 0 0 0 0 3 0.87 0.87 0.85 0.98 1.79 −0.13 −0.26 −0.41 −0.43 0.36 0 0 −0.01 −0.04−0.04  4 0.87 0.9 0.87 1.03 1.73 −0.13 −0.23 −0.36 −0.33 0.40 0 0 0 0 0 5 0.85 0.86 1.05 0.94 1.7 −0.15 −0.29 −0.24 −0.3 0.40 0 0 0 0 0  6 0.850.89 0.99 1.09 1.58 −0.15 −0.26 −0.27 −0.18 0.40 0 0 0 0 0  7 0.85 0.870.98 0.91 1.79 −0.15 −0.28 −0.3 −0.39 0.40 0 0 0 0 0  8 0.85 0.93 0.880.89 1.8 −0.15 −0.22 −0.34 −0.45 0.35 0 0 0 −0.05 −0.05  9 0.86 0.890.95 1.15 1.55 −0.14 −0.25 −0.3 −0.15 0.40 0 0 0 0 0 10 0.85 0.87 0.870.94 1.79 −0.15 −0.28 −0.41 −0.47 0.32 0 0 −0.01 −0.08 −0.08 11 0.860.91 0.85 1 1.78 −0.14 −0.23 −0.38 −0.38 0.40 0 0 0 0 0 12 0.86 0.891.03 1 1.62 −0.14 −0.25 −0.22 −0.22 0.40 0 0 0 0 0 13 0.85 0.87 1.030.96 1.69 −0.15 −0.28 −0.25 −0.29 0.40 0 0 0 0 0 14 0.86 0.93 1.04 1.051.52 −0.14 −0.21 −0.17 −0.12 0.40 0 0 0 0 0 15 0.87 0.91 1.01 0.94 1.67−0.13 −0.22 −0.21 −0.27 0.40 0 0 0 0 0 16 0.87 0.9 0.93 0.87 1.8 −0.13−0.23 −0.3 −0.43 0.37 0 0 0 −0.03 −0.03 17 0.87 0.85 0.86 1.15 1.65−0.13 −0.28 −0.42 −0.27 0.38 0 0 −0.02 −0.02 −0.02 18 0.85 0.88 1.041.07 1.56 −0.15 −0.27 −0.23 −0.16 0.40 0 0 0 0 0 19 0.87 0.92 0.91 1.091.61 −0.13 −0.21 −0.3 −0.21 0.40 0 0 0 0 0 20 0.87 0.89 1.04 1 1.6 −0.13−0.24 −0.2 −0.2 0.40 0 0 0 0 0 AVE 0.86 0.89 0.96 1.01 1.67 −0.14 −0.25−0.29 −0.28 0.39 0.00 0.00 0.00 −0.01 −0.01

TABLE 6 5 × 2 Liter CCPD Therapy with Negative UF Limit Set to 30%Patient B DV/FV UF/FV Unused Fluid/FV Day 1 2 3 4 5 6 7 1 2 3 4 5 6 7 12 3 4 5 6 7  1 0.87 0.93 0.94 0.98 1.68 −0.13 −0.2 −0.26 −0.28 0.40 0 00 0 0  2 0.87 0.85 0.92 1.08 1.62 −0.13 −0.28 −0.36 −0.28 0.34 0 0 −0.06−0.06 −0.06  3 0.85 0.93 1.05 1.08 1.49 −0.15 −0.22 −0.17 −0.09 0.40 0 00 0 0  4 0.87 0.9 0.91 1.1 1.6 −0.13 −0.23 −0.32 −0.22 0.38 0 0 −0.02−0.02 −0.02  5 0.86 0.91 0.95 0.93 1.7 −0.14 −0.23 −0.28 −0.35 0.35 0 00 −0.05 −0.05  6 0.87 0.85 1.03 0.9 1.7 −0.13 −0.28 −0.25 −0.35 0.35 0 00 −0.05 −0.05  7 0.86 0.91 0.93 0.92 1.7 −0.14 −0.23 −0.3 −0.38 0.32 0 00 −0.08 −0.08  8 0.87 0.88 0.99 0.12 1.54 −0.13 −0.25 −0.26 −0.14 0.40 00 0 0 0  9 0.87 0.89 0.91 1.06 1.64 −0.13 −0.24 −0.33 −0.27 0.37 0 0−0.03 −0.03 −0.03 10 0.86 0.85 1.05 1.13 1.51 −0.14 −0.29 −0.24 −0.110.40 0 0 0 0 0 11 0.85 0.9 0.91 1.1 1.6 −0.15 −0.25 −0.34 −0.24 0.36 0 0−0.04 −0.04 −0.04 12 0.86 0.91 1.02 1.11 1.5 −0.14 −0.23 −0.21 −0.1 0.400 0 0 0 0 13 0.85 0.85 1.05 1.14 1.51 −0.15 −0.3 −0.25 −0.11 0.40 0 0 00 0 14 0.85 0.9 1.05 1 1.6 −0.15 −0.25 −0.2 −0.2 0.40 0 0 0 0 0 15 0.860.93 0.87 0.97 1.66 −0.14 −0.21 −0.34 −0.37 0.29 0 0 −0.04 −0.11 −0.1116 0.85 0.85 0.97 1.15 1.55 −0.15 −0.3 −0.33 −0.18 0.37 0 0 −0.03 −0.03−0.03 17 0.87 0.87 0.92 0.95 1.66 −0.13 −0.26 −0.34 −0.39 0.27 0 0 −0.04−0.13 −0.13 18 0.87 0.93 0.94 1.05 1.61 −0.13 −0.2 −0.26 −0.21 0.40 0 00 0 0 19 0.85 0.93 0.85 1.01 1.63 −0.15 −0.22 −0.37 −0.36 0.27 0 0 −0.07−0.13 −0.13 20 0.87 0.9 1.05 1.05 1.53 −0.13 −0.23 −0.18 −0.13 0.40 0 00 0 0 AVE 0.86 0.89 0.97 1.04 1.60 −0.14 −0.25 −0.28 −0.24 0.36 0.000.00 −0.02 −0.04 −0.04

TABLE 7 5 × 2 Liter CCPD Therapy with Negative UF Limit Set to 25%Patient B DV/FV UF/FV Unused Fluid/FV Day 1 2 3 4 5 6 7 1 2 3 4 5 6 7 12 3 4 5 6 7  1 0.87 0.93 1.03 0.97 1.6 −0.13 −0.2 −0.17 −0.2 0.40 0 0 00 0  2 0.86 0.88 1 1.1 1.54 −0.14 −0.26 −0.26 −0.16 0.38 0 −0.01 −0.02−0.02 −0.02  3 0.87 0.89 0.91 1.1 1.55 −0.13 −0.24 −0.33 −0.23 0.32 0 0−0.08 −0.08 −0.08  4 0.87 0.93 0.97 0.87 1.65 −0.13 −0.2 −0.23 −0.360.29 0 0 0 −0.11 −0.11  5 0.86 0.89 1 1.01 1.64 −0.14 −0.25 −0.25 −0.240.40 0 0 0 0 0  6 0.87 0.92 0.88 0.88 1.57 −0.13 −0.21 −0.33 −0.45 0.120 0 −0.08 −0.28 −0.28  7 0.86 0.87 0.93 0.94 1.54 −0.14 −0.27 −0.34 −0.40.14 0 −0.02 −0.11 −0.26 −0.26  8 0.86 0.93 0.89 1.09 1.56 −0.14 −0.21−0.32 −0.23 0.33 0 0 −0.07 −0.07 −0.07  9 0.87 0.87 0.91 0.89 1.54 −0.13−0.26 −0.35 −0.46 0.08 0 −0.01 −0.11 −0.32 −0.32 10 0.85 0.85 1.04 0.941.59 −0.15 −0.3 −0.26 −0.32 0.27 0 −0.05 −0.06 −0.13 −0.13 11 0.85 0.860.91 1.14 1.47 −0.15 −0.29 −0.38 −0.24 0.23 0 −0.04 −0.17 −0.17 −0.17 120.87 0.86 0.88 0.87 1.49 −0.13 −0.27 −0.39 −0.52 −0.03 0 −0.02 −0.16−0.43 −0.43 13 0.86 0.9 0.94 1.06 1.59 −0.14 −0.24 −0.3 −0.24 0.35 0 0−0.05 −0.05 −0.05 14 0.85 0.92 0.87 1.14 1.51 −0.15 −0.23 −0.36 −0.220.29 0 0 −0.11 −0.11 −0.11 15 0.87 0.88 0.87 0.98 1.52 −0.13 −0.25 −0.38−0.4 0.12 0 0 −0.13 −0.28 −0.28 16 0.87 0.92 0.91 0.9 1.6 −0.13 −0.21−0.3 −0.4 0.20 0 0 −0.05 −0.2 −0.2 17 0.87 0.86 1.04 1.14 1.47 −0.13−0.27 −0.23 −0.09 0.38 0 −0.02 −0.02 −0.02 −0.02 18 0.86 0.89 0.98 1.041.61 −0.14 −0.25 −0.27 −0.23 0.38 0 0 −0.02 −0.02 −0.02 19 0.85 0.850.88 1.1 1.43 −0.15 −0.3 −0.42 −0.32 0.11 0 −0.05 −0.22 −0.29 −0.29 200.87 0.85 1.05 1.07 1.53 −0.13 −0.28 −0.23 −0.16 0.37 0 −0.03 −0.03−0.03 −0.03 AVE 0.86 0.89 0.94 1.01 1.55 −0.14 −0.25 −0.31 −0.29 0.260.00 −0.01 −0.07 −0.14 −0.14

TABLE 8 5 × 2 Liter CCPD Therapy with Negative UF Limit Set to 20%Patient B DV/FV UF/FV Unused Fluid/FV Day 1 2 3 4 5 6 7 1 2 3 4 5 6 7 12 3 4 5 6 7  1 0.85 0.85 0.92 0.97 1.32 −0.15 −0.3 −0.38 −0.41 −0.09 0−0.1 −0.28 −0.49 −0.49  2 0.85 0.89 1.03 0.93 1.51 −0.15 −0.26 −0.23−0.3 0.21 0 −0.06 −0.09 −0.19 −0.19  3 0.87 0.91 0.92 1.1 1.48 −0.13−0.22 −0.3 −0.2 0.28 0 −0.02 −0.12 −0.12 −0.12  4 0.85 0.9 1.02 0.871.52 −0.15 −0.25 −0.23 −0.36 0.16 0 −0.05 −0.08 −0.24 −0.24  5 0.87 0.860.97 0.94 1.43 −0.13 −0.27 −0.3 −0.36 0.07 0 −0.07 −0.17 −0.33 −0.33  60.87 0.89 0.89 0.91 1.41 −0.13 −0.24 −0.35 −0.44 −0.03 0 −0.04 −0.19−0.43 −0.43  7 0.86 0.92 0.99 1.04 1.54 −0.14 −0.22 −0.23 −0.19 0.35 0−0.02 −0.05 −0.05 −0.05  8 0.85 0.86 0.97 1.14 1.37 −0.15 −0.29 −0.32−0.18 0.19 0 −0.09 −0.21 −0.21 −0.21  9 0.87 0.93 0.88 0.91 1.48 −0.13−0.2 −0.32 −0.41 0.07 0 0 −0.12 −0.33 −0.33 10 0.86 0.85 0.92 0.92 1.34−0.14 −0.29 −0.37 −0.45 −0.11 0 −0.09 −0.26 −0.51 −0.51 11 0.85 0.890.91 0.85 1.39 −0.15 −0.26 −0.35 −0.5 −0.11 0 −0.06 −0.21 −0.51 −0.51 120.86 0.92 0.87 1.14 1.43 −0.14 −0.22 −0.35 −0.21 0.22 0 −0.02 −0.17−0.18 −0.18 13 0.85 0.87 0.9 1.01 1.34 −0.15 −0.28 −0.38 −0.37 −0.33 0−0.08 −0.26 −0.43 −0.43 14 0.85 0.89 0.98 0.97 1.46 −0.15 −0.26 −0.28−0.31 0.15 0 −0.06 −0.14 −0.25 −0.25 15 0.87 0.9 1 0.93 1.54 −0.13 −0.23−0.23 −0.3 0.24 0 −0.03 −0.06 −0.16 −0.16 16 0.87 0.85 0.86 0.94 1.3−0.13 −0.28 −0.42 −0.48 −0.18 0 −0.08 −0.3 −0.58 −0.58 17 0.87 0.9 1.010.95 1.55 −0.13 −0.23 −0.22 −0.27 0.28 0 −0.03 −0.05 −0.12 −0.12 18 0.870.88 0.86 1.07 1.36 −0.13 −0.25 −0.39 −0.32 0.04 0 −0.05 −0.24 −0.36−0.36 19 0.86 0.93 1 1.12 1.47 −0.14 −0.21 −0.21 −0.09 0.38 0 −0.01−0.02 −0.02 −0.02 20 0.87 0.85 0.96 0.94 1.4 −0.13 −0.28 −0.32 −0.380.02 0 −0.08 −0.2 −0.38 −0.38 AVE 0.86 0.89 0.94 0.98 1.43 −0.14 −0.25−0.31 −0.33 0.11 0.00 −0.05 −0.16 −0.29 −0.29

With the negative UF Limit set at 20%, neither Patient A nor Patient Bencounters a drain/fill volume ratio that exceeds 1.6 during the courseof the twenty therapies comprising data contained in Tables 4 and 8,each therapy including five cycles. The unused fluid/fill volume ratiowith the 20% negative UF limit in Tables 4 and 8 averages 25% and 29%,which means that 25% and 29% of 2000 ml (500 ml to 580 ml) of dialysissolution is unused. Thus, system 10, using the negative UF limit todetermine when to short fill volumes without increasing the number ofcycles, would reduce the effectiveness of the 10,000 ml therapy byaround 5% (500/10,000=5%, to 580/10,000=5.8%).

Referring now to FIG. 11C, flow diagram 200 illustrates one embodimentof a system 10 in which CCPD therapy is intended and begun. In thisembodiment, the therapy may be switched to tidal therapy if the drainsare incomplete or if too much dialysis fluid is not being used. Themethod begins at oval 202. At block 204, the system 10 performs aninitial drain, followed by block 206 with a fill. Per block 260, fordrains after the initial drain, a shorter fill volume will be used,i.e., the fill is shorted, if the previous drain falls short of thetarget volume and the UF limit is exceeded. The user sets a programmablenegative UF limit, such as 40% negative UF, that is used to determinewhen to use shorter fill volumes after one or more incomplete drainswhen running a CCPD therapy, or if a switch has been made, when runninga Tidal therapy. Other limits may be used, as mentioned above for theprocesses of FIGS. 11A and 11B.

After the fill, a dwell at block 208 is performed, the dwell calculatedas previously discussed. After the dwell, a drain is performed at block210. Based on the drain, the ratio of the drain volume to fill volume iscalculated, and the ratio for the last twenty drains is calculated andstored at block 212. At diamond 214, the system questions whether ashort fill was enabled for the previous cycle. If not, the ratio for theprevious twenty cycles is compared to determine whether any of thecycles had a ratio greater than 1.9 at diamond 220. If not, the processcontinues to block 226 where the number of remaining cycles and thedwell time is calculated. If any of the previous twenty cycles had aratio greater than 1.9, then the process enables short fills at the setlimit for negative UF, such as 40% UF, at block 222, and then proceedsto block 224.

Returning to diamond 214, if a short fill was enabled for a previouscycle, the process continues to diamond 216. At this point, the ratiosare analyzed to determine whether the ratio exceeded 1.6 for five of thetwenty previous cycles. Other embodiments may use other benchmarks thanfive of the previous twenty cycles, for example, four or six of theprevious ten cycles. If yes, the negative UF limit may be reset orlowered 10% and the process continued to block 224. If not, the processalso continues to block 224. At block 224, the patient fill volume isreset to the negative UF limit minus the accumulated negative UF. Forall the eventualities from blocks 222 and 224, and diamonds 214, 216 and220, the next step is block 226, at which the remaining number of cyclesand the dwell time for each is calculated.

For CCPD therapies, system 10 calculates the remaining number of CCPDcycles using the equation: Cycles Remaining=(total remaining therapyvolume−last fill volume (if any))/(programmed fill volume). For Tidaltherapies after an incomplete tidal drain, or after a complete fulldrain, system 10 calculates the remaining number of tidal cycles usingthe equation: Cycles Remaining=1+(Remaining Therapy Volume−FillVolume−Last Fill Volume)/(Tidal PerCent*Fill Volume). For Tidaltherapies after a complete tidal drain, system 10 calculates theremaining number of tidal cycles using the equation: CyclesRemaining=(Remaining Therapy Volume−Last Fill Volume)/(TidalPerCent*Fill Volume).

At diamond 228 if the fractional number of cycles exceeds 0.85, thenumber of cycles is rounded up to the nearest integer, per block 230. Atdiamond 232, system 10 compares the number of remaining cycles to zero.If the number of cycles remaining is greater than zero, the next fill isperformed, per block 206 and the process is repeated. If the number ofcycles is zero, the decision tree proceeds to diamond 234. If noadditional cycles were required in ten or more of the previous twentytherapies, the therapy is complete, per block 240. If additional cycleswere required in ten or more of the previous twenty therapies, diamond236 asks whether the current therapy is tidal (not CCPD). If the currenttherapy is tidal and is not CCPD, a recommendation is made for the nexttherapy to reduce the tidal volume by 10% in block 242. Therapy isadjudged complete for this particular therapy at block 240. Returning toblock 236, if the patient is presently using CCPD therapy, andadditional cycles were required in ten or more (half of more) of theprevious twenty therapies, a switch to 75% tidal therapy is recommendedfor the next therapy, after which the present therapy is complete.

Returning to diamond 228, if the fractional number of cycles is lessthan 0.85, the process moves to diamond 244, and the number offractional cycles is compared to 0.40. If the fractional number ofcycles is less than 0.40, the remaining number of cycles is truncated atblock 258 and the truncated or rounded down number of cycles is comparedto zero at block 232. If the number of remaining cycles is zero, theprocess follows the decision tree discussed above for diamond 234. Ifthe number of remaining cycles is an integer of 1 or more, the next fillis performed, per block 206.

Returning to diamond 244, if the fractional cycle remaining exceeds 0.4,a truncated number or rounded down number of cycles is used to calculatean increased fill volume at block 246. At block 248, the increased fillvolume based on the lower number of cycles is compared with the fillvolume based on the present prescription. The fill volume is calculatedto use the total therapy volume in the rounded down or truncated numberof cycles. The volumes are calculated as follows:higher fill volume=(remaining therapy volume−last fill volume)/roundeddown number of cycles.

If the ratio of the increased fill volume to prescribed fill volumebased on the lower number cycles is less than 1.05 (i.e., the increaseis less than 5%), as seen at diamond 248, system 10 resets the fillvolume for the next fill to the calculated increased fill volume atblock 250. The system then uses the truncated number of cycles, perblock 258, and returns through comparison diamond 232 to the next fillat block 206 or the decision tree at block 234. The ratio at block 248may be greater than 1.05, reflecting a significant increase in the fillvolume of the next cycle compared with the most recent. In order toavoid such abrupt changes, the system 10 at block 252 then rounds up thepreviously-truncated number of cycles (from block 246) and thencalculates a decreased fill volume using the higher number of cycles.The calculation used is:lower fill volume=(remaining therapy volume−last fill volume)/rounded upnumber of cycles.

The system 10 then uses this rounded-up number and a decreased fillvolume at block 254 for the next cycle. This decreased fill volume isnoted and is tracked at block 256 as an added cycle. The added cycle isnoted in comparison diamond 234.

Example for Patient C, per Table 9 and FIG. 11C: The negative UF limitmay be combined with the Unused fluid volume limit to better control theoperation of system 10, as seen in FIG. 11C. Table 9 contains foursub-tables, three similar to the others discussed above, and a fourthsub-table that depicts the actual fill volume/programmed fill volume(Actual FV/Programmed FV). This fourth sub-table demonstrates that theincreased fill volume due to incomplete drains, in this case, does notexceed 20% of the programmed fill volume, as was the case above in theExample for Patient A and Patient B. However, in this case, a cycle isadded any time the Unused Fluid/Fill Volume ratio in any of columns 3through 5 goes more negative than −0.40. In fifteen of the 20 therapiesall of the available fluid is used (see column 6, “0” unused fluid/FVratio).

TABLE 9 5 × 2 Therapy Changes to 2 × 2 + 3 shorted + 1 with new fillvolume (remainder of fluid) CCPD Therapy with Negative UF Limit Set to20% Patient C DV/FV UF/FV Unused Fluid/FV Day 1 2 3 4 5 6 1 2 3 4 5 6 12 3 4 5 6  1 0.86 0.87 0.85 0.9 0.96 1.59 −0.14 −0.27 −0.42 −0.52 −0.560.03 0 0 −0.07 −0.29 −0.61 0  2 0.86 0.87 0.94 0.94 1.4 −0.14 −0.27−0.33 −0.39 0.01 0 0 −0.07 −0.2 −0.39  3 0.85 0.87 0.94 0.93 1.38 1.4−0.15 −0.28 −0.34 −0.41 −0.03 0.37 0 0 −0.08 −0.22 −0.43 0  4 0.85 0.850.86 0.9 0.91 1.67 −0.15 −0.3 −0.44 −0.54 −0.63 0.04 0 0 −0.1 −0.34−0.68 0  5 0.85 0.87 0.87 1 1.31 1.3 −0.15 −0.28 −0.41 −0.41 −0.1 0.20 00 −0.08 −0.29 −0.5 0  6 0.87 0.87 0.95 0.93 1.43 −0.13 −0.26 −0.31 −0.380.05 0 0 −0.06 −0.17 −0.35  7 0.87 0.87 0.91 1.01 1.39 −0.13 −0.26 −0.35−0.34 0.05 0 0 −0.06 −0.21 −0.35  8 0.86 0.86 0.95 0.91 1.39 1.4 −0.14−0.28 −0.33 −0.42 −0.03 0.37 0 0 −0.08 −0.21 −0.43 0  9 0.85 0.86 0.850.93 1.05 1.5 −0.15 −0.29 −0.44 −0.51 −0.46 0.04 0 0 −0.09 −0.33 −0.64 010 0.85 0.85 0.91 0.91 0.99 1.6 −0.15 −0.3 −0.39 −0.48 −0.49 0.11 0 0−0.1 −0.29 −0.57 0 11 0.87 0.85 0.94 1 1.38 −0.13 −0.28 −0.34 −0.34 0.040 0 −0.08 −0.22 −0.36 12 0.87 0.86 0.86 0.92 0.92 1.62 −0.13 −0.27 −0.41−0.49 −0.57 0.05 0 0 −0.07 −0.28 −0.57 0 13 0.85 0.87 0.86 1.03 1.3 1.5−0.15 −0.28 −0.42 −0.39 −0.09 0.41 0 0 −0.08 −0.3 −0.49 0 14 0.85 0.850.88 1.04 1.28 1.45 −0.15 −0.3 −0.42 −0.38 −0.1 0.35 0 0 −0.1 −0.32 −0.50 15 0.85 0.87 0.88 0.9 0.9 1.63 −0.15 −0.28 −0.4 −0.5 −0.6 0.03 0 0−0.08 −0.28 −0.58 0 16 0.87 0.86 0.88 1.01 1.34 1.3 −0.13 −0.27 −0.39−0.38 −0.04 0.26 0 0 −0.07 −0.26 −0.44 0 17 0.85 0.85 0.94 0.92 1.341.45 −0.15 −0.3 −0.36 −0.44 −0.1 0.35 0 0 −0.1 −0.26 −0.5 0 18 0.86 0.860.88 0.85 0.9 1.7 −0.14 −0.28 −0.4 −0.55 −0.65 0.05 0 0 −0.08 −0.28−0.63 0 19 0.87 0.86 0.86 1.05 1.32 1.36 −0.13 −0.27 −0.41 −0.36 −0.040.32 0 0 −0.07 −0.28 −0.44 0 20 0.87 0.87 0.89 1 1.37 −0.13 −0.26 −0.37−0.37 0 0 0 −0.06 −0.23 −0.4 AVE 0.86 0.89 1.00 1.37 1.21 1.50 −0.14−0.28 −0.38 −0.43 −0.22 0.28 0.00 0.00 −0.08 −0.26 −0.49 0.00 ActualFV/Programmed FV Day 1 2 3 4 5 6  1 1.00 1.14 1.20 1.20 0.81 0.81  21.00 1.14 1.20 1.20 1.20 1.20  3 1.00 1.15 1.20 1.20 0.72 0.72  4 1.001.15 1.20 1.20 0.84 0.84  5 1.00 1.15 1.20 1.20 0.75 0.75  6 1.00 1.131.20 1.20 1.20 1.20  7 1.00 1.13 1.20 1.20 1.20 1.20  8 1.00 1.14 1.201.20 0.72 0.72  9 1.00 1.15 1.20 1.20 0.82 0.82 10 1.00 1.15 1.20 1.200.79 0.79 11 1.00 1.13 1.20 1.20 1.20 1.20 12 1.00 1.13 1.20 1.20 0.790.79 13 1.00 1.15 1.20 1.20 0.75 0.75 14 1.00 1.15 1.20 1.20 0.75 0.7515 1.00 1.15 1.20 1.20 0.79 0.79 16 1.00 1.13 1.20 1.20 0.72 0.72 171.00 1.15 1.20 1.20 0.75 0.75 18 1.00 1.14 1.20 1.20 0.82 0.82 19 1.001.13 1.20 1.20 0.72 0.72 20 1.00 1.13 1.20 1.20 1.20 1.20 AVE 1.00 1.141.20 1.20 0.88 0.88

At the present time in 2008, most APD patients perform CCPD therapiesand there is no UF limit that results in an automatic shorting of thenext fill when a drain is not complete. Succeeding fills are always fullif the minimum drain volume was achieved during the previous drain. Anegative UF alarm is sounded if the accumulation of negative UF exceedsan alarm limit, typically set at 50% of the programmed fill volume. Thetracking of negative UF is based solely upon the volume drained less thevolume filled and does not account for ultra-filtration across theperitoneal membrane. The method described herein tracks the ratio of thevolume drained to the prescribed fill volume. Per the discussion abovefor FIG. 11C, if this ratio exceeds 1.9 once in every twenty drains, orif the ratio exceeds 1.6 five times in every twenty drains, the systemwill suggest that the user Enable the negative UF limit algorithm tolimit fill volumes and add cycles as necessary to reduce the magnitudeand incidence of increased intra-peritoneal volume.

FIG. 11C illustrates how the system monitors CCPD drain ratios and usesthe results to suggest when the user should enable the negative UF limitalgorithm to limit IIPV. The system will lower the UF threshold forshorting fills to limit the incidence of IIPV and low drain alarms. Thesystem will also suggest when the user should switch to a tidal therapy.

As described above for block 220, system 10 suggests activating thenegative UF limit algorithm if a drain volume/fill volume ratio exceeds1.9 during any of the Drains 2 through N drains (the last drain) in morethan one per twenty therapies.

At block 216, system 10 suggests lowering the negative UF limit settingif a drain/fill volume exceeds 1.6 during the first drain through Ndrains (the last drain) more than x occurrences in y therapies, e.g.,more than five times in twenty therapies. Other embodiments may useother limits, for the drain volume/fill volume ratio, for the number oftherapies in which a particular high ratio is encountered, or for both.

At diamond 220, system 10 monitors the drain to fill volume ratio andalso monitors the unused fluid/fill volume (FV) ratio and determineswhether the unused fluid/FV exceeds a certain ratio in a number ofcycles in a given therapy. For example, system 10 may set 40% (a ratioof 0.40) in any of cycles 2 through N−2 of N (that is, thesecond-next-to last, e.g., cycles 2-3 in a five-cycle therapy or cycles2-4 in a six-cycle therapy). In another example, the system may use 50%(a ratio of 0.50) in cycles 2 through N−1 (next to last), e.g., cycles2-4 in a five-cycle therapy or cycles 2-5 in a six-cycle therapy, forwhich an example is given in Table 9. Note that in Table 9, the UF/FVratio for day 1 at cycle 2 is −0.27, which exceeds the negative 20%limit that was used when generating Table 9. Thus, the next cycle isshorted by 7%, leading to an Unused Fluid/FV for day 1, cycle 3, of−0.07. At cycle 3, the UF/FV ratio rises to −0.42, i.e., again negativeUF. Cycle 4 is now shorted 29% (−0.29=−0.07−0.22 for Unused Fluid/FV atday 1, cycle 4, since −0.42−(−0.20)=−0.22). The result of Cycle 4 isstill negative UF (−0.52) and cycle 5 is again shorted (−0.61 UnusedFluid/FV). Since 0.61 exceeds 0.50 (50%), the number of cycles isincreased by 1 (adding a sixth cycle) and the target patient fill volumeis decreased, so that the remainder of the dialysis fluid is used in thesixth cycle.

At block 254, using the 50% example and if unused fluid/FV exceeds 50%,system 10 increases the remaining number of cycles by 1 and distributesthe remaining dwell time and remaining therapy volume evenly over theincreased remaining number of cycles (see, e.g., in Table 9, day 1,number of cycles increased to six when the unused fluid/FV ratio exceeds0.50 (actually 0.61) in the column for cycle 4. At blocks 228 and 244after the next fill cycle, system 10 calculates the unused Fluid/FVratio (remaining cycler fraction) to zero for a therapy with a cycleadded.

Returning to diamond 244, if the unused fluid/FV ratio is less than 40%,the system instead moves to diamond 258 and through eventually todiamond 234 when all of the available fluid has been delivered. Atdiamond 234, system 10 monitors the frequency at which an increasednumber of cycles is needed to prevent fluid loss in excess of a givenpercentage A (e.g., 50%) of the fill volume. If the frequency is equalto or greater than 50% of the time (e.g., ten times or more over twentytherapies), system 10 at block 236 suggests that the patient beconverted to a tidal therapy since the patient is already in effectperforming an 85% tidal therapy. For example, switching to a 75% tidaltherapy may be a more effective use of the fluid volume that isavailable while minimizing the magnitude of excess intra-peritonealvolume and reducing the frequency of low drain volume alarms.

At block 256, system 10 uses UF trending discussed below to monitor the75% (or current) tidal therapy. At diamond 234, system 10 determineswhether the frequency at which the patient's residual volume has to beoffset over time is greater than a specified percentage of the time,e.g., 50% percent of the time. If so, system 10 suggests switching to alower percentage, e.g., 65%, tidal therapy at block 242 for the nexttherapy. If the residual volume still has to be offset greater than acertain percentage, e.g., 50%, of the time, as determined at diamond234, the loop continues to lower the tidal percentage until the residualdrain volume is lowered to an acceptable level, at which time the methodof logic flow diagram 200 ends. Tidal therapies are still effective withregard to solute removal for tidal percentages as low as about 50%.Ultra-filtration can be maintained at tidal percentages lower than 50%.

If a patient still has drain issues with a tidal percentage of around50%, the patient is a candidate for multi-pass continuous flowperitoneal dialysis (Multi-Pass CFPD) as discussed in US Pat. Appl.Publ. 20040019320, which is hereby incorporated herein by reference.Multi-Pass CFPD continuously fills and drains the patient using either adual lumen catheter as discussed in US Pat. Appl. Publ. 20030204162 andU.S. Pat. No. 6,976,973, both of which are hereby incorporated herein byreference. Alternatively, two single lumen catheters may be used. Thepatient is only drained to below the prescribed fill volume prior to thestart of the Multi-Pass CFPD therapy and at the end of the Multi-PassCFPD therapy. Low drain volume alarms are virtually eliminated. CheckPatient line alarms can still occur if the patient line becomes kinked.

Optimizing Tidal Therapies Via UF Trending

As discussed above, there is a need for an automated peritoneal dialysistherapy that ensures the use of all of the prescribed dialysis solution,can finish on time, can minimize if not eliminate low drain volumealarms and can prevent the volume of fluid in the patient's peritoneumfrom exceeding the programmed fill volume by more than about the amountof expected ultrafiltration (“UF”) obtained from the patient over onedwell cycle. Properly estimating a patient's UF for a given solution istherefore important. It is contemplated that system 10, instead of usingpredicted UF values, uses recently trended UF values for the same typeof treatment using the same type of PD solution.

Referring now to FIG. 12, a trend for a 50% tidal therapy withprogrammed UF based upon trending is shown for both 1.5% and 2.5%dextrose concentration dialysis solution types. The trended 50% therapyfor the patient shows that about 2400 ml of UF is removed if thatpatient uses 2.5% dextrose and 1600 ml of UF is removed if that patientuses 1.5% dextrose.

The total UF is then divided out over the number of night therapy cycles(fills/dwells/drains) to determine the UF per cycle, e.g., four cyclesresulting in 600 ml UF for 2.5% dextrose and 400 ml of UF for 1.5%dextrose. The values of 600 ml and 400 ml are added to the prescribedfill volumes to determine a patient's maximum allowable IPV in oneembodiment. The maximum IPV is then used to determine the volume ofresidual fluid that should remain in the patient's peritoneum after adrain. For example, if the patient's maximum IPV is 2600 ml (2000 mlfill plus 600 ml UF), the residual volume for a fifty percent tidaldrain should be 1300 ml. Just as important, the cycler of system 10 willattempt to remove 1300 ml over the drain.

FIG. 12 shows, for each dextrose level, each day's UF entry. System 10in one embodiment determines the actual UF removed from the patient overthe course of a night therapy (not counting last fill or day exchange).The actual UF measurement assumes a complete (to zero ml) drain prior toboth the first fill and last or day fill (if performed). In this manner,System 10 knows how much fresh dialysate has been delivered to thepatient and how much spent dialysate (including UF) has been removedfrom the patient over the nightly treatment. The difference is the nighttherapy UF, which is logged into data storage for the patient, theconcentrate and therapy, and used to further update the trend. UF can beplotted as a single day (FIG. 12) or as a rolling average (FIG. 17).U.S. patent application Ser. No. 12/170,220 (“the TrendingApplication”), entitled “Dialysis System Having Trending and AlertGeneration,” filed Nov. 3, 2008, the pertinent portions of which areincorporated expressly herein by reference and relied upon, disclosesdifferent rolling average UF trends and trends using statistical processcontrol (“SPC”) for alarming/alerting. Such trends can be usedalternatively or additionally to the single day trend shown in FIG. 12.

FIGS. 13, 14, 15 and 16 illustrate four different treatment scenarios.The continuous line indicates the volume of fluid that system 10delivers and removes from the patient over time. The dashed lineindicates the actual volume of fluid residing in the patient (“IPV”) atany given point in time. The difference between the machinedelivered/removed volume and the actual volume is the patient's UF. Thedotted line indicates the actual UF removed from the patient over time.

FIG. 13 illustrates a 50% tidal therapy using 1.5% dextrose dialysate.The trended 1600 ml total UF for such treatment is recalled from memoryof system 10 and used to simulate the patient's actual IPV. The 1600 mlUF is split amongst ten treatments, yielding 160 ml removed per cycle asshown in FIG. 13. FIG. 14 illustrates a 50% tidal therapy using 1.5%dextrose dialysate. The trended 2400 ml total UF for this treatment isrecalled from memory of system 10 and used to simulate the patient'sactual IPV. The 2400 ml UF is also split amongst ten treatments,yielding 240 ml removed per cycle as shown in FIG. 14.

FIG. 15 again illustrates a 50% tidal therapy using 1.5% dextrosedialysate. The trended 1600 ml total UF for such treatment is recalledfrom memory of system 10 and used to simulate the patient's actual IPV.Here, however, the total UF removed is only 1280 ml, short by 320 ml.The 1280 ml UF is again split amongst ten treatments, yielding 128 mlremoved per cycle as shown in FIG. 15. Because the predicted UF from thepatient's actual trend set a good starting place, and because the 50%tidal therapy is forgiving in terms of having enough planned residualvolume to accept lower than expected residual volumes (here due to lessUF than expected), the treatment is able to use all of the prescribedsolution, maintain the prescribed dwell times and finish therapy ontime.

FIG. 16 again illustrates a 50% tidal therapy using 1.5% dextrosedialysate. The trended 1600 ml total UF for such treatment is recalledfrom memory of system 10 and used to simulate the patient's actual IPV.Here, however, the total UF removed is more than expected, 1920 ml,greater by 320 ml. The 1920 ml UF is again split amongst ten treatments,yielding 192 ml removed per cycle as shown in FIG. 16. Again, thepredicted UF from the patient's actual trend set a good starting place.The 50% tidal therapy is forgiving in terms of setting the plannedresidual volume high enough so that the planned drain can take placeeach cycle, which at least does not add to the effect of the additionalUF. The treatment is thus able to use all of the prescribed solution,maintain prescribed dwell times, and finish therapy on time.

In the therapies of FIGS. 15 and 16, all of the dialysis solution isused, the dwell times are as prescribed, the potential for low drainalarms is minimized and the maximum patient volume is limited to lessthan that with CCPD therapies. The trending of the UF (based uponosmotic concentration) accordingly allows tidal treatments to be used ina very advantageous manner.

In one embodiment, system 10 trends a running average of the patient'sUF and displays same for both the patient and clinician. The displayedtrended time interval can be varied from a week to a month to multiplemonths (see also Trending Application). The user in one embodiment canscroll forward or may scroll backward to see the results for thepreceding ninety days. System 10 in one embodiment enables the user toselect the prescription ID axis (e.g., via input device 22 (FIG. 1) or atouch screen operable with video monitor 20), after which system 10changes the display to that shown in FIG. 12, in which two or moredifferent prescriptions or dextrose levels are trended independently.

FIG. 17 shows which dialysate is used on a given day (prescription 1 orprescription 2), the desired UF volume, and a trended rolling seven dayaverage actual UF. System 10 can therefore use as its predicted UF theprevious day's UF volume (if the same therapy and dialysate is used) oran averaged UF data point for the same dialysate/treatment. As discussedin the Trending Application, the UF trends, e.g., FIGS. 12 and 17, maybe maintained at the logic implementer of the cycler 12 or at a remoteserver, e.g., located at a dialysis clinic or doctor's office. In eithercase, networked communication can allow any one or more of the patient,clinician and doctor to view the UF trend.

As discussed, using trended UF values allows the programmed UF to bewithdrawn during the tidal therapy to be predicted quite accurately. Theactual patient volume (“IPV”) will likewise trend very close to the IPVthat the APD cycler 12 expects to be in the patient's peritoneum asillustrated in FIGS. 13 to 16. System 10 in one embodiment is programmedsuch that if the UF trend changes by more than a preset percentage, thesystem alerts the user so that he/she can consult a PD doctor orclinician. System 10 in one embodiment automatically adjusts the UF thatis programmed for the osmotic agent being used to use the most recent UFtrended data point.

Alternatively, the machine alerts the patent to make a change to theprogrammed UF, so that the user knows of the change. To this end, eachosmotic agent or dextrose level dialysate can be associated with adifferent dialysate ID or number, which the patient enters into thesystem. System 10 then calls up a screen for the particular dialysate,so that the patient can make the machine suggested change. The TrendingApplication referenced above describes situations in which the patient'sdoctor or clinician is notified when the patient's UF trends too faraway from an expected level for a particular dialysate.

It is important to drain the patient fully at the start of any APDtherapy. This holds true for the 50% tidal therapy with UF based upontrending of multiple concentration osmotic agents. In the initial andfinal drains, however, the patient can be sitting up and will typicallydrain better, compared with draining when lying down in a supineposition. The patient can also move around a little since he/she will beawake and is not inconvenienced when doing so.

System 10 in one embodiment knows how much fluid resides in thepatient's peritoneum at the start of a therapy. The system remembers thetype and volume that it filled the day before for a last fill. System 10in one embodiment trends initial drain volumes and posts an alert ifdrain flow stops before the normal initial drain volume has beenrecovered knowing the previous day's last fill volume and dextroselevel. System 10 can also query the user regarding any day exchange thatthe patient made the previous day not using machine 12 as a possibleexplanation for an abnormal initial drain.

FIG. 18 shows an alternative embodiment in which system 10 and machine12 continuously remove UF during dwell so that the patient's IPV doesnot increase over the dwell. Here again, it is important to know the UFaccurately for the patient and a particular dextrose level, in order toknow how much fluid to remove from the patient over the dwell. The UFvolume divided by the dwell time informs system 10 and cycler 12 of theproper flow rate at which to remove the UF volume from the patient.

While 50% tidal percentage with trended UF provides one very suitabletherapy (see predicted results for different patients below), thepercentage can be varied if desired or if a different percentage ispredicted for a particular patient to have better clearance. Forpatients that typically drain well, the percentage can be higher, e.g.,65% or 75% and still allow prevent the vast majority of low drainalarms, prevent short fills, and complete therapy on time with theprescribed amount of dwell. Percentages below 50% are also possible.

Predicted Therapy Outcomes

Simulations were performed on APD Therapies (Tables 10 and 11) using PDprediction software called Renalsoft™, provided by the assignee of thepresent disclosure. The Trending Application referenced above discussesthe prediction software in detail. The simulations were performed toshow two different comparisons (i) 50% tidal (using trended UFprediction) versus standard APD Therapy (complete drains, no shorting offills) and (ii) 85% tidal to simulate CCPD with 15% shorted next fillsversus standard APD Therapy (complete drains, no shorting of fills). Thesoftware compared the therapies for the three patient body sizes and thefour different PET categories, yielding twelve different patient typesshown in Table 10.

TABLE 10 Definition of Patient Types Patient Type Description: BSA Sizeand PET Category 1 BSA-Less Than-1.71-PET-HIGH 2 BSA-1.71-2.00-PET-HIGH3 BSA-Greater Than-2.00-PET-HIGH 4 BSA-Less Than-1.71-PET-HIGH-AVE 5BSA-1.71-2.00-PET-HIGH-AVE 6 BSA-Greater Than-2.00-PET-HIGH-AVE 7BSA-Less Than-1.71-PET-LOW 8 BSA-Greater Than-2.00-PET-LOW 9 BSA-LessThan-1.71-PET-LOW-AVE 10 BSA-Less Than-1.71-PET-LOW-AVE 11BSA-1.71-2.00-PET-LOW-AVE 12 BSA-Greater Than-2.00-PET-LOW-AVE

As seen in Table 11, in all instances, the 50% tidal therapy resulted inhigher creatinine clearances when compared to a standard CCPD therapywith full drains and no shorted fills. The results were consistent forboth dry days and wet days. As shown, 50% tidal therapy based uponactual patient UF trending with both 1.5% and 2.5% dextrose dialysateoffer superior clearances. And as discussed herein, 50% tidal therapy isshown to have fewer low drain volume alarms and better control of thevolume of fluid in the patient when compared to conventional APD.

TABLE 11 Creatinine Clearance Increase (PerCent) for 50% Tidal over APDNo Last Fill = Dry Day Last Fill = Wet Day 50% Tidal Standard APD 50%Tidal Standard APD Creatinine Creatinine Creatinine Creatinine PatientClearance Clearance Percent Patient Clearance Clearance Percent TypeL/wk/1.73 m² L/wk/1.73 m² Increase Type L/wk/1.73 m² L/wk/1.73 m²Increase 1 49.98 48.36 3.3% 1 70.01 68.34 2.4% 2 48.62 47.08 3.3% 267.01 65.43 2.4% 3 39.06 37.45 4.3% 3 53.90 52.26 3.1% 4 44.70 41.876.8% 4 64.04 61.19 4.7% 5 35.63 32.03 11.2% 5 53.51 51.67 3.6% 6 35.3833.32 6.2% 6 50.63 48.57 4.2% 7 25.36 22.45 13.0% 7 43.41 40.46 7.3% 823.51 20.99 12.0% 8 39.30 36.78 6.9% 9 24.58 22.31 10.2% 9 37.47 35.206.4% 10 36.73 33.57 9.4% 10 55.74 52.55 6.1% 11 30.90 28.10 10.0% 1148.53 45.70 6.2% 12 26.56 24.10 10.2% 12 41.56 39.08 6.3%

An alternative to the 50% tidal therapy is to short a subsequent fill ina CCPD therapy that experiences an incomplete drain when attempting tobring the patient's IPV to zero. The subsequent fill can be shorted bythe amount that the previous drain was short. In this manner, system 10limits the amount that the patient can be overfilled to the amount offluid that has been ultrafiltered from the patient. Assuming, forexample, that each drain is 15% short except for the last drain, theresulting change in creatinine clearance is shown in Table 12. For mostpatients, the clearances are reduced primarily because there is unusedfluid left in the supply/heater bags at the end of the therapy. In theexample illustrated below, 1080 ml out of a total therapy volume of12000 ml (Dry Day) or 14000 ml (Wet Day) is not used.

TABLE 12 Creatinine Clearances for Smart APD (85% Tidal) Versus APD NoLast Fill = Dry Day Last Fill = Wet Day Standard Standard 85% Tidal APD85% Tidal APD Creatinine Creatinine Creatinine Creatinine PatientClearance Clearance Percent Patient Clearance Clearance Percent TypeL/wk/1.73 m² L/wk/1.73 m² Change Type L/wk/1.73 m² L/wk/1.73 m² Change 146.12 48.36 −4.6% 1 66.11 68.34 −3.3% 2 44.92 47.08 −4.6% 2 63.27 65.43−3.3% 3 35.82 37.45 −4.4% 3 50.63 52.26 −3.1% 4 40.78 41.87 −2.6% 460.08 61.19 −1.8% 5 32.77 32.03 2.3% 5 50.60 51.67 −2.1% 6 32.32 33.32−3.0% 6 47.55 48.57 −2.1% 7 22.70 22.45 1.1% 7 40.71 40.46 0.6% 8 21.1520.99 0.8% 8 36.90 36.78 0.3% 9 22.27 22.31 −0.2% 9 35.12 35.20 −0.2% 1033.28 33.57 −0.9% 10 52.23 52.55 −0.6% 11 27.95 28.10 −0.5% 11 45.5345.70 −0.4% 12 23.97 24.10 −0.5% 12 38.93 39.08 −0.4%

The data in Table 12 predicts a reduced creatinine clearance when system10 shorts succeeding fills by the amount that preceding drains fallshort of recovering 100% of the previous fill volume. This is to beexpected because some of the fresh dialysis solution was not used.Tables 10 and 11 show that a 50% tidal therapy is at least as effectiveas a properly performed APD CCPD therapy and does not run the risk oflow drain alarms or fill shorts that the APD CCPD therapy runs.

Patient Recirculation

Single lumen patient lines have a recirculation volume (volume of fluidleft in the patient line at the end of drain and returned at the startof the next fill) that reduces the therapeutic affect of the therapy.For example, if the internal volume of the patient line 38 d (FIG. 1) is42 ml and the fill volume is 1000 ml, 42/1000*100%=4.2% of the availablefluid is wasted. Patients with larger fill volumes can use longerpatient lines 38 d without losing a larger percentage of their dialysisfluid. Patients with smaller fill volumes sometimes have to use shorterpatient lines 38 d with smaller inside diameters to avoid wasting ahigher percentage of their dialysis solution.

The 50% tidal therapy discussed herein will drain and fill moving asmaller solution volume when compared to a standard APD therapy. Apatient with a 2000 ml fill volume on 50% tidal is accordingly wastingthe same percentage of dialysis solution as a patient with a 1000 mlfill volume on full drain APD.

In one embodiment, system 10 addresses the recirculation issue bylimiting the length of the standard patient line to about twenty-twofeet instead of the thirty-three feet that currently can be used.

Alternately, patient line 38 d is a dual lumen patient line, so thatonly the transfer set volume is recirculated. Dual lumen patient line 38d does not result in an increase in the size of the patient's transferset. Using dual lumen patient line 38 d allows the length of the line tobe any desired, suitable length, and the same disposable set 30 (FIG. 1)and cassette 50 (FIG. 2) can be used for both the low fill mode and thestandard fill mode. One suitable dual lumen patient line 38 d and methodtherefore is disclosed in U.S. patent application Ser. No. 11/773,795,entitled, “Dialysis System Having Dual Patient Line Connection AndPrime”, filed Jul. 5, 2007, the relevant portion of which isincorporated herein by reference and relied upon.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

1. An automated peritoneal dialysis system comprising: at least onedialysis fluid pump configured to pump a dialysis fluid to and from apatient over a treatment, the treatment including a plurality of patientfills, dwells, and drains; at least one conduit positioned and arrangedto allow effluent dialysis fluid to be removed from the patient duringthe plurality of patient drains; at least one processor; and at leastone memory device storing a plurality of instructions executed by the atleast one processor to: (i) control the dialysis fluid pumped by the atleast one dialysis fluid pump to and from a patient over the treatmentand (ii) use at least one trended ultrafiltration (“UF”) data point forthe patient to determine an amount of effluent dialysis fluid to removefrom the patient through the at least one conduit during at least one ofthe patient drains.
 2. The dialysis system of claim 1, wherein thetrended UF data point is an averaged UF data point.
 3. The dialysissystem of claim 1, the trended UF data point obtained from a trendmaintained by one of the at least one processor/memory device and aremote server in communication with the logic implementer.
 4. Thedialysis system of claim 1, wherein the trended UF data point is a mostrecent data point on a trend of multiple UF data points.
 5. The dialysissystem of claim 1, wherein the trended UF data point is specific to aparticular dialysis fluid.
 6. The dialysis system of claim 1, the atleast one processor/memory device configured to use the at least one UFdata point with a programmed fill volume to determine the amount ofeffluent dialysis fluid to remove.
 7. The dialysis system of claim 6,wherein the at least one processor/memory device is configured todetermine the amount of effluent dialysis fluid to remove as apercentage of at least one of the UF data point plus the programmed fillvolume.
 8. The dialysis system of claim 7, wherein the percentage is setlow enough to ensure that the amount of effluent dialysis fluid can beremoved in each of a plurality of patient drains.
 9. The dialysis systemof claim 6, wherein the at least one processor/memory device isconfigured to determine the amount of the effluent dialysis fluid toremove by adding the UF data point to the programmed fill volume. 10.The dialysis system of claim 1, wherein the at least oneprocessor/memory device is configured to (i) determine an actual amountof UF removed over the treatment and (ii) use the actual amount removedto update a UF trend including the UF data point.
 11. The dialysissystem of claim 1, which includes an initial drain in which the UF datapoint is not used to determine an amount of effluent dialysis fluidremoved from the patient.
 12. An automated peritoneal dialysis systemcomprising: at least one dialysis fluid pump configured to pump adialysis fluid to and from a patient over a treatment, the treatmentincluding a plurality of patient fills, dwells and drains; at least onedialysis fluid conduit constructed and arranged to allow effluentdialysis fluid to be removed from the patient during the plurality ofpatient drains; at least one processor; and at least one memory devicestoring a plurality of instructions executed by the at least oneprocessor to: (i) control the dialysis fluid pumped by the at least onedialysis fluid pump to and from a patient over the treatment, (ii)access a trend of ultrafiltration data points for the patient, and (iii)use at least one of the UF data points to predict the patient'sintra-peritoneal volume (“IPV”) at an end of at least one of theplurality of patient dwells to determine at least one of (a) asubsequent fill volume, and (b) a subsequent drain volume.
 13. Thedialysis system of claim 12, the UF data point used being at least oneof a (i) a most recent UF data point; and (ii) an averaged UF datapoint.
 14. The dialysis system of claim 12, the at least oneprocessor/memory device further configured to update the UF trend basedon actual UF removed over the treatment.
 15. The dialysis system ofclaim 12, the at least one processor/memory device configured to add ameasured patient fill amount to the at least one UF data point todetermine the IPV.
 16. The dialysis system of claim 12, the at least oneprocessor/memory device further configured to subtract a measuredpatient drain amount from the IPV to determine a residual amount ofeffluent left within the patient after a drain.
 17. An automatedperitoneal dialysis system comprising: at least one dialysis fluid pumpconfigured to pump a dialysis fluid to and from a patient over atreatment, the treatment including a plurality of patient fills, dwellsand drains; at least one conduit positioned and arranged to alloweffluent fluid to be removed from the patient during at least one of thepatient drains; at least one processor; and at least one memory devicestoring a plurality of instructions executed by the at least oneprocessor to: (i) control the dialysis fluid pumped by the at least onedialysis fluid pump to and from a patient over the treatment, (ii)access a trend of ultrafiltration data points for the patient, and (iii)use one of the UF data points in a tidal treatment having a reduceddrain volume to predict a residual volume of effluent fluid left in thepatient's peritoneum after at least one of the plurality of patientdrains.
 18. The dialysis system of claim 17, the at least oneprocessor/memory device configured to add a measured fill amount to theUF data point to determine an intra-peritoneal volume (“IPV”) for thepatient and then subtract a measured drain amount to determine theresidual volume.